Arvados

A logging middleware in lib/cmd that sets up logging and profiling according to cli flags. This way, our various applications don't need to handle that themselves.

It should use a context passed to RunCommand, which can then just call `ctxlog.FromContext(ctx)` and have logging/profiling set up for it.

The implementation could be vaguely similar to cmd.Multi in lib/cmd -- so cmd/arvados-client could say handler = cmd.LogOptions(cmd.Multi(...)).

As part of this story, some existing commands will need to be adapted (e.g. lib/costanalyzer and lib/deduplicationreport already handle the -loglevel argument).