…7225)

> [!NOTE]
> This PR was created with the assistance of GitHub Copilot.

## Summary

Enable the CoreCLR runtime pack for `android-arm` (armeabi-v7a) by
removing the ARM architecture restriction and adding CI pipeline
support.

## Changes

- **`eng/Subsets.props`** — Remove `arm` from the blocked Android
architectures list (keep `x86` blocked). The original blocker was
`fseeko`/`ftello` not being available below API level 24 (#111665). With
the minimum API level being raised to 24 in #126838, this no longer
applies.
- **`eng/pipelines/runtime.yml`** — Add `android_arm` to the CoreCLR
Android CI platform list.
-
**`eng/pipelines/extra-platforms/runtime-extra-platforms-android.yml`**
— Add `android_arm` to the extra-platforms CoreCLR job.
- **`eng/pipelines/coreclr/templates/helix-queues-setup.yml`** — Add
`android_arm` Helix queue mapping using the same
`Windows.11.Amd64.Android` queues as `android_arm64`.

## What already works (no changes needed)

- Platform matrix definition (`android_arm` already defined in
`platform-matrix.yml`)
- Native build tooling (NDK `arm → armeabi-v7a` mapping)
- Packaging RIDs (`linux-bionic-arm` in `netcoreappRIDs.props` and
`KnownFrameworkReference`)
- Libraries Helix queues (already handle `android_arm`)
- CoreCLR CMake/JIT (no ARM32+Android-specific blocks)

## Dependencies

This PR depends on #126838 (raise `AndroidApiLevelMin` from 21 to 24)
and should be merged after it.

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Jan Kotas <jkotas@microsoft.com>

Conflict resolutions:

- SslStream.IO.cs / SslStream.Protocol.cs: reconciled main's
  SslStreamPal.CertValidationInCallback gating + split inner overload
  with this branch's 'ref SslPolicyErrors' change. Callers seed
  sslPolicyErrors = SslPolicyErrors.None before VerifyRemoteCertificate
  so the inner overload can accumulate errors without overwriting the
  Android platform-trust verdict.

- Interop.OpenSsl.cs (Linux callback) and FakeSslStream.Implementation.cs:
  updated to the new 'ref SslPolicyErrors' signature.

- pal_sslstream.c: took main's removal of ApplyLegacyAndroidSNIWorkaround
  (legacy API 21-23 code became unreachable after dotnet#126838
  bumped the Android minimum API level to 24). Reverted to 'char*' for
  AndroidCryptoNative_SSLStreamSetTargetHost; further 'const char*' /
  API 21-23 dead-code scrub will land in a follow-up commit.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

After dotnet#126838 bumped the Android minimum API level to 24,
the UNSUPPORTED_API_LEVEL return code is unreachable: SNI setup is
supported on every API the runtime can target. The earlier merge
already removed ApplyLegacyAndroidSNIWorkaround; this commit removes
the remaining managed/native plumbing and the now-unused resource
string.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Enable the CoreCLR runtime flavor for the armeabi-v7a ABI, following the
same pattern as android-arm64 and android-x64.

Changes:
- Set SupportCoreCLR=True for armeabi-v7a in Ndk.projitems.in
- Add ApiLevelNonMono metadata and corresponding property/placeholder
- Add Microsoft.Android.Runtime.CoreCLR.36.1.android-arm to workload manifest

Depends on dotnet/runtime#127225 and dotnet/runtime#126838 (API level 24).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

dotnet/runtime builds all runtimes (MonoVM, CoreCLR, NativeAOT) against
API level 24. The separate AndroidMinimumNonMonoApiLevel property and all
NonMono-specific API level plumbing in dotnet/android was unnecessary
since MonoVM was already being compiled at API 24 by runtime.

Changes:
- Bump AndroidMinimumDotNetApiLevel from 21 to 24
- Remove AndroidMinimumNonMonoApiLevel and all related properties,
  constants, template placeholders, and conditional logic
- Simplify CMake presets: nonmono-common-* now inherit from common-*
- Remove ArchToApiLevelNonMono dictionary from XABuildConfig
- Simplify MonoAndroidHelper.GetMinimumApiLevel (no runtime branching)
- Remove MinimumNonMonoApiLevel from GenerateSupportedPlatforms task
- Remove runtime-conditional AndroidMinimumSupportedApiLevel items

### Remove nonmono CMake preset indirection

Remove the nonmono-common-* preset definitions (now redundant) and
update all consumers to inherit from common-arm64-v8a / common-x86_64
directly.

Related: dotnet/runtime#126838

### Fix CheckSignApk tests for API 24+ APK signing

With min SDK 24+, apksigner uses v2/v3 signature schemes only and skips
v1 JAR signing, so META-INF/MANIFEST.MF is no longer present in signed
APKs. Replace the ZIP entry check with an AssertApkIsSigned helper that
runs 'apksigner verify' to validate signatures regardless of scheme.

AAB signing still uses jarsigner (which always produces META-INF), so
those assertions are unchanged.

### Remove redist-nativeaot directory; use unified redist for all runtimes

With API level 24 unified across all runtimes, the separate
redist-nativeaot directory (which copied CRT/DSO stubs from the API 24
sysroot) is redundant — the regular redist directory already uses API 24.

Remove the NativeAOT-specific copy in Step_Android_SDK_NDK, point the
NativeAOT pack at the common redist directory, and remove the
redist-nativeaot glob from native.targets.

### Skip BuildXamarinFormsMapsApplication for NativeAOT

R8 9.1.31 crashes with a NullPointerException when processing
androidx.core.core.aar (LocationManagerCompat) in the old AndroidX
packages used by Xamarin.Forms. This only manifests for NativeAOT
because it's the only runtime that runs as Release (which enables R8).

Remove NativeAOT from the test parameters entirely and simplify
the remaining code (IsRelease is always false now).

### Use XamarinAndroidApplicationProject in CheckNothingIsDeletedByIncrementalClean

XamarinFormsAndroidApplicationProject uses old AndroidX packages that
trigger an R8 9.1.31 internal crash (NullPointerException processing
LocationManagerCompat). The test only validates incremental clean
behavior, not Xamarin.Forms-specific functionality.

### Fix NativeAOT runtime pack missing toolchain libraries

The redist-nativeaot removal (cd7f135) accidentally dropped the
toolchain library entries (crtbegin_so.o, crtend_so.o, libc++_static.a,
libc++abi.a, libclang_rt.builtins, libunwind.a) from the NativeAOT
runtime pack. These are required for NativeAOT's native linking step.

Share the toolchain entries between CoreCLR and NativeAOT since both
do native linking. Also consolidate the system lib stubs (libc.so, etc.)
into an unconditional ItemGroup since all runtimes need them.

### Include .o files in NativeAOT runtime pack

The NativeAOT section in native.targets only copied .a files from the
redist directory into the runtime pack, but not .o files (crtbegin_so.o,
crtend_so.o). These CRT object files are needed by the workload-provided
linker (now the default for NativeAOT builds).

Unify the CoreCLR and NativeAOT redist copy blocks since they now use
the same redist directory and need the same file types.

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: simonrozsival <374616+simonrozsival@users.noreply.github.com>
Co-authored-by: Jonathan Peppers <jonathan.peppers@microsoft.com>