Authenticator has configurable logging levels

[jtuttle]

We should add a configurable debug-level logger and include some debug logging for events such as finding the client cert. This logger should be enabled when the environment variable value DEBUG=true is specified.

[izgeri]

It would be preferable to enable more customizable log levels because the INFO level logging for this library is quite verbose.

We import these packages in Secretless, and would like to only output the Secretless logs and suppress the authenticator client library logs (which are pretty verbose) unless there are errors, and maybe warnings.