Add pre-commit

[lethosor]

pre-commit is a tool that provides basic linting functionality out of the box, and is relatively easy to set up locally so that it runs on every commit. There is a complementary CI service that can automate these checks on PRs. We could also integrate formatters to address #1535, eventually.

My recommendation for now is to enable this in (in order of priority):

• dfhack
• scripts
• df-structures
• stonesense
• dfhack-ci
• (maybe, low-priority) clsocket and any other deps we maintain

(Opening an issue to cross-link PRs in our different repos.)