[MachineVerifier] Report errors from one thread at a time (#111605)

Create the `ReportedErrors` class to track the number of reported errors
during verification. The class will block reporting errors if some other
thread is currently reporting an error.

I've encountered a case where there were many different verifications
reporting errors at the same time on different threads. This ensures
that we don't start printing the error from one case until we are
completely done printing errors from other cases. Most of the time
`AbortOnError = true` so we usually abort after reporting the first
error.

Depends on https://github.com/llvm/llvm-project/pull/111602.

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