Remove .mvid section.

[teo-tsirpanis]

Fixes #82653.

Partially reverts #19133

As explained in the linked issue, the CopyRefAssembly task is now able to use System.Reflection.Metadata to read the reference assembly's MVID from the Module table, which means that we no longer have to duplicate it in the .mvid PE section.

This PR updates CopyRefAssembly to use SRM, and updates PeWriter to stop writing the .mvid section in reference assemblies.

Microsoft Reviewers: Open in CodeFlow

[teo-tsirpanis]

This is a behavior change, as SRM will throw on invalid files, while the previous MvidReader did not. There is code in CopyRefAssembly that handles the MvidReader throwing, which makes me not sure of what the intention is.

Is this change OK, or should we update CopyRefAssembly to swallow the exceptions during MVID reading?

[AlekseyTs]

This PR updates CopyRefAssembly to use SRM, and updates PeWriter to stop writing the .mvid section in reference assemblies.

Is this safe to do? Is it possible that some existing tools will stop working if the section isn't present?

[teo-tsirpanis]

From what I'm seeing here, there are a few external tools (F# and dnlib) that write an .mvid section, but none that reads it. I don't think it's likely that a tool would have a strong dependency on this section's existence, partly because it's not emitted in assemblies used at runtime.

[jaredpar]

Waiting for confirmation from msbuild about these dependencies