Add CI leg to test strict indentation

[auduchinok]

Adds a new CI leg to test the indentation/parser changes independently from other preview changes, as suggested in #15637 (comment).

[auduchinok]

@vzarytovskii Could you check what's wrong with the new leg when you have time, please?
There's an error about publishing build artifacts, and I don't know what to do with it.

[vzarytovskii]

@vzarytovskii Could you check what's wrong with the new leg when you have time, please? There's an error about publishing build artifacts, and I don't know what to do with it.

I'm actually not sure custom flag is passed there, I think build script might be treating it as its own flag, and not passed to msbuild?

[vzarytovskii]

@auduchinok yeah, build script failed and there were no logs to upload:
https://dev.azure.com/dnceng-public/public/_build/results?buildId=346335&view=logs&j=70e6e619-3cf7-5833-fa8f-6499093f7398&t=20ac6483-4e71-5107-5aa7-585726d1ae96

A bit misleading message though.

[auduchinok]

This is ready.

Thanks for the help! 🙂