[tests] Upgrade tests/monotouch-test to NUnit v4 Assert.That syntax

[rolfbjarne]

Convert classic NUnit assertions to NUnit v4's constraint-based
Assert.That syntax across the monotouch-test project.

Also improve test failure diagnostics by:

• Swapping literal/actual argument order in Assert.That calls so that
  on failure NUnit reports 'Expected: But was: '
  instead of the confusing reverse

• Splitting compound boolean assertions (e.g. nalCount == 4 &&
  paramCount == 2) into individual constraint-based assertions that
  report each value independently on failure

• Converting Assert.That(x == y, Is.True) non-operator value checks
  to proper Assert.That(x, Is.EqualTo(y)) form

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[vs-mobiletools-engineering-service2]

✅ [PR Build #9b026d1] Build passed (Detect API changes) ✅

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Hash: 9b026d10de0542a60a366fdcdf4ff0a4d7c5d146 [PR build]

[vs-mobiletools-engineering-service2]

✅ [PR Build #9b026d1] Build passed (Build packages) ✅

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Hash: 9b026d10de0542a60a366fdcdf4ff0a4d7c5d146 [PR build]

[vs-mobiletools-engineering-service2]

✅ API diff for current PR / commit

NET (empty diffs)

• iOS: vsdrops gist ( No breaking changes )
• tvOS: vsdrops gist ( No breaking changes )
• MacCatalyst: vsdrops gist ( No breaking changes )
• macOS: vsdrops gist ( No breaking changes )

✅ API diff vs stable

NET (empty diffs)

• iOS: vsdrops gist ( No breaking changes )
• tvOS: vsdrops gist ( No breaking changes )
• MacCatalyst: vsdrops gist ( No breaking changes )
• macOS: vsdrops gist ( No breaking changes )

ℹ️ Generator diff

Generator Diff: vsdrops (html) vsdrops (raw diff) gist (raw diff) - Please review changes)

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Hash: 9b026d10de0542a60a366fdcdf4ff0a4d7c5d146 [PR build]

[vs-mobiletools-engineering-service2]

✅ [PR Build #9b026d1] Build passed (Build macOS tests) ✅

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Hash: 9b026d10de0542a60a366fdcdf4ff0a4d7c5d146 [PR build]

[vs-mobiletools-engineering-service2]

🚀 [CI Build #9b026d1] Test results 🚀

Test results

✅ All tests passed on VSTS: test results.

🎉 All 183 tests passed 🎉

Tests counts

✅ cecil: All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (iOS): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (MacCatalyst): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (macOS): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (Multiple platforms): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (tvOS): All 1 tests passed. Html Report (VSDrops) Download
✅ framework: All 2 tests passed. (⚠️ Html Report Publish failed ⚠️) Download
✅ fsharp: All 4 tests passed. Html Report (VSDrops) Download
✅ generator: All 5 tests passed. Html Report (VSDrops) Download
✅ interdependent-binding-projects: All 4 tests passed. Html Report (VSDrops) Download
✅ introspection: All 6 tests passed. Html Report (VSDrops) Download
✅ linker: All 44 tests passed. Html Report (VSDrops) Download
✅ monotouch (iOS): All 18 tests passed. Html Report (VSDrops) Download
✅ monotouch (MacCatalyst): All 20 tests passed. Html Report (VSDrops) Download
✅ monotouch (macOS): All 20 tests passed. Html Report (VSDrops) Download
✅ monotouch (tvOS): All 18 tests passed. Html Report (VSDrops) Download
✅ msbuild: All 2 tests passed. Html Report (VSDrops) Download
✅ sharpie: All 1 tests passed. Html Report (VSDrops) Download
✅ windows: All 3 tests passed. Html Report (VSDrops) Download
✅ xcframework: All 4 tests passed. [attempt 2] Html Report (VSDrops) Download
✅ xtro: All 1 tests passed. [attempt 2] Html Report (VSDrops) Download

macOS tests

✅ Tests on macOS Monterey (12): All 5 tests passed. Html Report (VSDrops) Download
✅ Tests on macOS Ventura (13): All 5 tests passed. Html Report (VSDrops) Download
✅ Tests on macOS Sonoma (14): All 5 tests passed. Html Report (VSDrops) Download
✅ Tests on macOS Sequoia (15): All 5 tests passed. Html Report (VSDrops) Download
✅ Tests on macOS Tahoe (26): All 5 tests passed. Html Report (VSDrops) Download

Linux Build Verification

✅ Linux build succeeded

Pipeline on Agent
Hash: 9b026d10de0542a60a366fdcdf4ff0a4d7c5d146 [PR build]