[cmd/opampsupervisor] Add configurable supervisor logging

[dpaasman00]

Component(s)

cmd/opampsupervisor

Is your feature request related to a problem? Please describe.

Right now the supervisor strictly logs to stdout which can be a pain point when trying to monitor the supervisor's logs.

Describe the solution you'd like

Add the option to configure how the supervisor logs data like log level and output destinations.

Describe alternatives you've considered

You could just pipe the process output to a file, but that seems tedious. That approach also doesn't allow configuring log level output or other helpful logging configuration options.

Additional context

I have a solution in progress for this feature request.

[github-actions]

Pinging code owners:

• cmd/opampsupervisor: @evan-bradley @atoulme @tigrannajaryan @BinaryFissionGames

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