Ability to control log level of tsh cli

[mvgijssel]

What would you like Teleport to do?

I would like there to be an option to mute WARNING messages from the tsh cli.

What problem does this solve?

I'm trying to use Teleport in combination with the SSH backend of the testinfra library https://testinfra.readthedocs.io/en/latest/backends.html#ssh in vgijssel/setup#325. Currently the tests from testinfra fail, because the stdout of the ssh commands the library is trying to do is filled with warning of incompatible options:

WARNING: Option 'ConnectTimeout' is not supported.\nWARNING: Option 'ControlMaster' is not supported.\nWARNING: Option 'ControlPersist' is not supported.\n

If it would be possible to configure the log level of the tsh cli like tsh --log-level=error ssh ... and to mute the errors, it would make it easier to integrate into libraries like testinfra.

If a workaround exists, please include it.

Hacky stdout parsing trying to remove the warnings.