Remove ISourceFile Uri

[shenglol]

Removes the obsolete ISourceFile.Uri property and migrates remaining test helpers/call sites to use FileHandle.Uri / IOUri instead.

Summary:

• Remove Uri from the ISourceFile contract and concrete source file classes.
• Update test template helpers to accept IOUri.
• Move remaining test usage from sourceFile.Uri to sourceFile.FileHandle.Uri.
• Update the extension config inheritance test to use InMemoryTestFileSet.

Validation:

• dotnet build .\Bicep.sln /property:GenerateFullPaths=true /consoleloggerparameters:NoSummary

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 29124273362)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 29124273362

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 29124273362"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 29124273362

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 29124273362"