This PR integrates craft-cli with the current "state of the art" implemented by Starbase. It's a huge changeset because it's a merge of two distinct repositories, but the idea is that future merges will be easier/less painful. The general strategy was this: First I merged `starbase/main` into this branch, and for the conflicts I preferred starbase's version for most cases, unless the fix was very straightforward. This merge is commit 13c852fd4e5f6ec77ed145b6b253d38f16e5d769. After that, I added commits to migrate craft-cli's way of doing things to starbase's. For example, the first commit after the merge removes `setup.py` and `setup.cfg` and adds the config to `pyproject.toml`. This migration was done manually and I inspected/tested the resulting wheel, etc. The next commits add fixes for the individual linters, coverage, and a bigger one for the docs. Then I removed the files that are no longer needed (like the Makefiles). Hopefully, the task of reviewing per-commit starting at that merge (or the one right after it, since it's hard to review the merge) won't be too onerous because each commit is reasonably self-contained; if it is, tell me and I can see about opening multiple PRs.