Organize / Cleanup Logging + Levels

[haileyschoelkopf]

We should do a pass through the codebase and unify log printing styles + re-check log levels.

Ideally a novice user should only see WARNING levels if they are doing something unintended / footgun-y and INFO levels should (theoretically) be ignorable if you're not a power user. DEBUG should refer to logs that are useful when trying to add a new task and not useful to see every run otherwise. We should try not to print too many logs in the default setting, except where we think it helps the average user (there should be an easily-accessible "almost-silent" mode.)

[haileyschoelkopf]

Listing some changes that pop out if I run into them.

• lm_eval/api/task#L701 should get a more informative log message?
• Phase out --write_out in favor of just logging some sample instances instead when using DEBUG log level?