[ci]: Support code diff coverage

[xumia]

Support code diff coverage

1. Support to add the pull request checks for Code diff coverage in GitHub.
2. Support to display the code diff coverage html report in Azure Pipelines.

[xumia]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[kcudnik]

how this entire feature should work ? is already framework for support that build in azpipeline and sairedis azpipeline configuration?

[xumia]

@kcudnik , I added an azure devops extension to support it, see https://github.com/Azure/sonic-build-web/tree/main/code-diff-coverage. Azure DevOps still does not support it. It is a workaround, so we do not need to change it in all sub-modules, only enable it by a variable flag.

[xumia]

@kcudnik , can we merge the code, there is one failure check, looks like it is not relative to the change.

[kcudnik]

your diff coverage plugin broken full coverage stats file by file:
https://dev.azure.com/mssonic/build/_build/results?buildId=39429&view=results

clicking you can't see any more how much covered is each added file , please revert your change or make it possible to view both results