Use tox and/or pre-commit for static analysis checks

[jakkdl]

check.sh is getting kinda bloated with the addition of isort, codespell, and check_type_completeness - and trying to read the output from it to figure out what actually failed is kind of a pain. I've been using tox and pre-commit locally to avoid having to deal with the shell scripts, and been copying over configuration and commands, and maybe it's about time to share that and maybe make it official instead.

Setting up test environments in tox would also help people testing on different python versions and the like, although I've had some troubles with test_exports/ from inside tox envs (having to mess with PY_IGNORE_IMPORTMISMATCH, custom install_commands, and the like. It's definitely doable though)