Cleanup Typescript imports in pre-commit

[pokey]

• Add import sorting. Probably should just use import/order, but if that doesn't work for some reason we could consider https://github.com/trivago/prettier-plugin-sort-imports, which is a prettier plugin
• Add eslint --fix back to pre-commit using a local hook to ensure version parity as described in Add pre-commit #637 (comment). Ensure that it is run on Typescript files as described in https://github.com/pre-commit/mirrors-eslint#using-eslint-with-pre-commit
• Add https://www.npmjs.com/package/eslint-plugin-unused-imports as eslint plugin, and configure it properly to remove imports
• While we're here, we could switch to running prettier using a local hook as well in order to maintain version parity with package.json

[phillco]

From the meetup: @pokey's main concern with doing this now is version skew between pre-commit's eslint and what's in package.json, as they should match, but pre-commit.ci only bumps the version in the pre-commit configuration, not the package.json.

Semi relatedly, we're also not thrilled with pre-commit.ci's lack of respect for semver. (And I find the fact that you have to pin versions in two places in the first place to be kind of sus)

Ideally https://github.com/renovatebot/renovate would be used to bump both locations together, but we're not quite ready to pull the trigger on that, because it looks like it wants to bump everything, opening a huge number of PRs. We'd like to enable automatic merging if tests pass for these types of procedural bumps (this would also be good to have in all of the other Talon repositories -- it currently feels like busywork), but things like the cheatsheet and website do not have good test coverage currently, and currently get automatically deployed, so we don't want to risk them suddenly breaking.

In the short term, we agreed that if we could add eslint to pre-commit config but tell pre-commit.ci not to bump it (and thus require that people bump both locations together manually), that would be fine for now to unblock this. This looks pretty easy to do.

That way, we get the benefits of automatic fixing on PRs (or locally), at the cost of slightly more work to bump eslint until we can set up something like renovate, but hopefully we run fix way more often than we bump eslint.

[auscompgeek]

In the short term, we agreed that if we could add eslint to pre-commit config but tell pre-commit.ci not to bump it (and thus require that people bump both locations together manually), that would be fine for now to unblock this. This looks pretty easy to do.

That way, we get the benefits of automatic fixing on PRs

Isn't that ci#skip configuration to skip the hook entirely on pre-commit.ci, hence we won't get autofixing on PRs?

[phillco]

Oops, you're right. It doesn't look like they separate skipping fixups from skipping version bumping for a particular hook. I guess we could maybe move to bumping versions of everything manually?