Update BitOperations callsites

[grant-d]

Update known callsites in CoreFX to use BitOperations
See #35606
And #34917

cc @tannergooding, @jkotas

[grant-d]

Looks like I may need to fix code depending on target.
Should I keep the legacy code as a software fallback for netstandard ?

build.cmd -restore -build -configuration Release -ci -buildtests -arch x86 -framework netfx …

PEHeaderBuilder.cs(68,69): error CS0103: The name 'BitOperations' does not exist in the current context [D:\a\1\s\src\System.Reflection.Metadata\src\System.Reflection.Metadata.csproj]

[tannergooding]

Should I keep the legacy code as a software fallback for netstandard

Yes, this will likely be required until BitOperations makes it into netstandard. CC @terrajobst

[jkotas]

Adding BitOperations to netstandard is not going to alleviate this.

The real problem is that System.Reflection.Metadata is targeting existing netstandard versions that is not changing anytime soon.

[grant-d]

Should I close this PR then - I am not sure it's worth it?

[jkotas]

I think the change in ManagedWebSocket.cs is good. The changes in System.Reflection.Metadata are not worth it.

[grant-d]

OK, manually reverted changes to System.Reflection.
The only real change is in ManagedWebSocket.cs, with some VS auto-format fixes in the reverted files.

[grant-d]

All the NetFx targets are going to have the same problem. I don't think multi-targeting is worth it in this case since after inlining it has no functional benefit. It's really just about pretty code.

[jkotas]

Ok, I have not realized that ManagedWebSocket.cs is included in netstandard project as well.