Warn when MetadataUpdaterSupport is false in dotnet watch

[jonathanpeppers]

Add the same hot reload support check for MetadataUpdaterSupport that already exists for StartupHookSupport. When MetadataUpdaterSupport is false (e.g. non-Debug configurations), dotnet watch now warns that the project does not support Hot Reload and suggests setting the property to True.

Changes

• BuildNames.cs — Added MetadataUpdaterSupport constant
• HotReloadAppModel.cs — Added a check: if MetadataUpdaterSupport is false, logs ProjectDoesNotSupportHotReload_Property warning and returns false. Includes a link to the CoreCLR MetadataUpdater.cs source.
• SourceFileUpdateTests.HotReloadNotSupported.cs — Added [InlineData("MetadataUpdaterSupport", "False")] test case

[Copilot]

Copilot wasn't able to review this pull request because it exceeds the maximum number of files (300). Try reducing the number of changed files and requesting a review from Copilot again.

[tmat]

Note that when PublishTrimmed is true the value of MetadataUpdaterSupport used to be false even in debug build. This was fixed by dotnet/runtime#127163

[tmat]

Actually, the fix dotnet/runtime#127163 only targets .NET 11 runtime. Instead of checking MetadataUpdaterSupport we might need to check Optimize and DebugType properties like VS does.

[jonathanpeppers]

Could a project set <MetadataUpdaterSupport>false</MetadataUpdaterSupport> as well?

What made me look at this, is this issue:

• Better support for non-standard $(Configuration) names #31918 (comment)

It made me wonder if hot reload works for a $(Configuration) named something like DebugProd or Prod.

[tmat]

Yes, MetadataUpdaterSupport can be set by project.

I think what we need to do is:
If TFV >= 11 then check MetadataUpdaterSupport, otherwise check DebugSymbols == true && Optimize == false.

VS currently does the latter. I'll change it to check the same condition as watch.