ComInterfaceGenerator uses Diagnostic in incremental pipeline, which do not compare as equal in Roslyn

[jtschuster]

Diagnostics won't be incremental in the generator pipeline: dotnet/roslyn#68291

Workaround is to create a DiagnosticTemplate record with all the information required to report the diagnostic, then build the diagnostic right before reporting it.

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Issue Details

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Diagnostics won't be incremental in the generator pipeline: dotnet/roslyn#68291

Workaround is to create a DiagnosticTemplate record with all the information required to report the diagnostic, then build the diagnostic right before reporting it.

Author:	jtschuster
Assignees:	jtschuster
Labels:	area-System.Runtime.InteropServices
Milestone:	-

[jkoritzinsky]

We should fix this for LibraryImport at the same time.

[jtschuster]

fixed in #86908