Use lint-staged to run prettier

[jeffposnick]

Fixes #2944, hopefully. It seems to work as expected when I tested on a Windows tablet using Power Shell, with node and npm manually installed.

This switches to using lint-staged to orchestrate that process instead of git-format-staged.

Also, when investigating this issue, I realized that the glob patterns in our .prettierignore were not configured properly, and there were a bunch of TypeScript source files that should have been formatted, but weren't. So the cosmetic fixes to all those files got picked up in this PR as well.

CC: @StephanBijzitter

[tropicadri]

TS lint is complaining of a couple of issues other than that it lgtm

[jeffposnick]

Some of the linting issues were introduced by prettier reformatting the code, so that our comments that disable eslint on the following line no longer applied to the line we expected...

That also made me realize that I neglected to add back the pre-push hook that runs our linting, since it's really silly to push to a PR only to find out that it fails CI. I've re-added that.

I also will update our guide to contributing code in a separate PR to clearly spell out what needs to be done to get up and running locally, including on Windows.