Implement analyzer that validates MetadataUpdateHandlerAttribute usage

[tmat]

Description

MetadataUpdateHandlerAttribute expects the specified type to declare certain methods as documented here:

https://learn.microsoft.com/en-us/dotnet/api/system.reflection.metadata.metadataupdatehandlerattribute?view=net-8.0#remarks

There is no design-time validation of this contract though. It would be useful to implement an analyzer and include it in the SDK.

It would prevent issues like https://github.com/dotnet/AspNetCore-ManualTests/issues/3086

Reproduction Steps

See https://github.com/dotnet/AspNetCore-ManualTests/issues/3086

Expected behavior

Analyzer should warn that the type does not implement required contract.

Actual behavior

No warning during build.

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

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