Backport XML docs for System.Diagnostics.FileVersionInfo from dotnet-api-docs

[Copilot]

Description

Backports XML documentation from dotnet-api-docs to the System.Diagnostics.FileVersionInfo source implementation.

Changes

• Source implementation (FileVersionInfo.cs): Added <summary>, <value>, <param>, and <returns> tags to all public members
• Documentation fixes: Corrected value documentation for int properties (FileBuildPart, FilePrivatePart, Product*Part) to return 0 instead of null when version info is missing (original dotnet-api-docs XML had incorrect null references for value types)

Note on Compiler-Generated Docs

This library keeps <UseCompilerGeneratedDocXmlFile>false</UseCompilerGeneratedDocXmlFile> in the project file because:

• The library uses GeneratePlatformNotSupportedAssemblyMessage which generates platform-not-supported stub files
• These generated stubs would require XML documentation to avoid CS1591 errors
• Per repository conventions, documentation should never be added to ref assemblies
• Therefore, compiler-generated docs cannot be enabled, and documentation remains in the source implementation only

Example

Properties now have complete inline documentation:

/// <summary>
/// Gets the build number of the file.
/// </summary>
/// <value>A value representing the build number of the file or 0 (zero) if the file did not contain version information.</value>
public int FileBuildPart { get; }

Original prompt

Please backport the XML docs from https://github.com/dotnet/dotnet-api-docs/blob/main/xml/System.Diagnostics/FileVersionInfo.xml to the source implementation and update the .csproj file to use the compiler generated docs. Follow the pattern in #124227.

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[gewarren]

@copilot Docs should never be added to the ref assembly.

[Copilot]

Removed the XML docs from the ref assembly in commit a640b63. Also restored UseCompilerGeneratedDocXmlFile=false in the csproj since enabling compiler-generated docs would require XML documentation in the generated platform-not-supported stubs, which would need to come from the ref assembly.

[gewarren]

@richlander @jeffhandley Is Copilot correct that there needs to be docs in the ref assembly here?

[dotnet-policy-service]

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