add python formatting and checking with ruff

[torcolvin]

This allows use of common editors that format with black or ruff. Adds CI to make sure it takes.

Otherwise, I kept accidentally autoformatting files when I did a fix and I had to revert to use an editor without automatic formatting turned on.

The first commit is github actions changes, the second commit just automatic formatting, and the third commit https://github.com/couchbase/sync_gateway/commit/3142d3106bbf3ceaa0572cfc86970ad4412b6499 is the manual changes I made. When reviewing, just look at {{.github}} folder and the third commit.