Tighten bounds checks around TextEncoder logic

- Replaces unsafe code with safe code where possible
- Fixes some surrogate pairs being misinterpreted
- Fixes dotnet#45994
- Ref: MSRC 62749 (CVE-2021-26701)

[release/6.0-preview1] Produce a .version file for Microsoft.NETCore.…

…App in the runtime layout. (dotnet#47736)

* Produce a .version file for Microsoft.NETCore.App in the runtime layout.

* Update src/installer/pkg/sfx/Microsoft.NETCore.App/Microsoft.NETCore.App.Runtime.sfxproj

* Update src/installer/pkg/sfx/Microsoft.NETCore.App/Microsoft.NETCore.App.Runtime.sfxproj

Co-authored-by: Jeremy Koritzinsky <jekoritz@microsoft.com>
Co-authored-by: Jeremy Koritzinsky <jkoritzinsky@gmail.com>

Merge in 'release/5.0' changes

Merge in 'release/5.0' changes

Skip some PKCS9 tests on NetFx (dotnet#45213)

Skip some PKCS9 tests on NetFx (dotnet#45213)

[release/5.0] [browser][crypto] Remove restraining not supported attr…

…ibute Primitives (dotnet#43441)

Co-authored-by: Kenneth Pouncey <kjpou@pt.lu>

[release/5.0] [browser][crypto] Remove restraining not supported attr…

…ibute Primitives (dotnet#43441)

Co-authored-by: Kenneth Pouncey <kjpou@pt.lu>

Fix System.Net.Sockets telemetry (dotnet#42726)

Leftover Utf8String defines are causing ILLinker warnings (dotnet#41680)

The CreateRuntimeRootILLinkDescriptorFile task, which generates most of S.P.CoreLib's ILLink.Descriptor file for coreclr, doesn't respect #ifdefs. So even though FEATURE_UTF8STRING is disabled in the release/5.0 branch, it is still generating entries for Char8 and Utf8String. But since these managed types do not exist, the ILLinker is raising warnings.

To fix this, comment the DEFINE_CLASS entries out of the header file.

Fix dotnet#41654