Backport XML documentation for CustomReflectionContext

[Copilot]

Description

Backports XML documentation from dotnet-api-docs to the runtime repository per #124227.

Changes:

• Added XML documentation to CustomReflectionContext class in src assembly with summary and simplified type-level remarks
• Added summary, param/return documentation, and short member-level remarks to all public/protected members in src assembly
• Type-level remarks in src include only a link to supplemental documentation: https://github.com/dotnet/docs/raw/main/docs/fundamentals/runtime-libraries/system-reflection-context-customreflectioncontext.md
• Member-level remarks provide brief contextual information (e.g., usage guidance for AddProperties and CreateProperty methods)
• Removed UseCompilerGeneratedDocXmlFile=false from csproj to enable compiler-generated XML documentation files
• Added <NoWarn>$(NoWarn);CS1591</NoWarn> to suppress missing XML documentation warnings in generated platform-not-supported stubs
• Ref assembly contains no XML documentation per established guidelines

Customer Impact

Developers using System.Reflection.Context will have IntelliSense documentation with summaries, parameter descriptions, and brief contextual remarks for all members, plus a link to comprehensive documentation showing how to customize reflection behavior through attribute manipulation and virtual properties.

Regression

No. Documentation-only change.

Testing

• Built successfully for all target frameworks (netstandard2.0, netstandard2.1, net10.0)
• XML documentation compiles without errors
• Compiler-generated XML documentation files are created successfully from src assembly
• Code review passed

Risk

Minimal. Documentation-only change with no runtime impact.

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[gewarren]

@copilot Please respond to feedback.

[Copilot]

@copilot Please respond to feedback.

Addressed all feedback in commit 865415d:

• Removed all XML documentation from the ref assembly
• Simplified the src file remarks to only include the supplemental docs link
• Removed detailed remarks from member methods
• Restored UseCompilerGeneratedDocXmlFile=false to prevent CS1591 errors

[Copilot]

Pull request overview

This PR backports XML documentation from dotnet-api-docs to the runtime repository for the CustomReflectionContext class, following the established pattern from PR #124227. The documentation provides IntelliSense support for developers using this reflection API.

Changes:

• Added comprehensive XML documentation to CustomReflectionContext class including type-level summary, simplified remarks with a link to supplemental documentation, and complete member-level documentation
• All public and protected members now have summaries, parameter descriptions, return value documentation, and brief contextual remarks where appropriate
• Followed the established convention of not adding documentation to ref assemblies

[gewarren]

@copilot Please update the .csproj file to use the compiler generated docs.

[Copilot]

@copilot Please update the .csproj file to use the compiler generated docs.

Updated the .csproj to use compiler-generated docs in commit ca89848. Also added minimal XML documentation to the ref assembly to prevent CS1591 errors in the generated netstandard2.0 platform-not-supported stub.

[gewarren]

@copilot please remove docs from ref assembly but keep changes to .csproj file.

[Copilot]

Removed XML docs from the ref assembly in commit 6c60cb8. Kept the .csproj change (no UseCompilerGeneratedDocXmlFile=false) and added NoWarn for CS1591 to suppress missing XML doc warnings in the generated netstandard2.0 platform-not-supported stub.