Python model logging

[mikealfare]

resolves #846 docs dbt-labs/docs.getdbt.com/#

Problem

We don't provide a standard way to enable logging for python models.

Solution

Put together some proposals for minimal permission workarounds as well as some potential implementations for down the road. This likely won't be merged, but will serve as a PoC.

Checklist

• [ ] I have read the contributing guide and understand what's expected of me
• [ ] I have run this code in development and it appears to resolve the stated issue
• [ ] This PR includes tests, or tests are not required/relevant for this PR
• [ ] This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX