chore: repo cleanup

[dummdidumm]

Housekeeping PR, mainly bumping packages (closes #12224)

• remove skipLibCheck because it would mean our own d.ts files aren't checked anymore. Instead bump a few packages and move deps around to get rid of the error for which it was introduced
• remove prettier from packages, everything runs through the root now (also better aligns with how you work with it in VS Code: no more config duplication needed)
• remove eslint from packages, run it once through the root now (revealed some inconsistencies and missing stuff, config tightened up as a result) (bump eslint while we're at it)
• bump a few other packages. Those not bumped are either not worth it (like @rollup/plugin-commonjs which introduces a bunch of new deps and otherwise has no observable changes for us) or the corresponding project (like svelte.dev) will be overhauled soon, anyway
• bumped JSOM which required adjusting a few tests

Before submitting the PR, please make sure you do the following

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• Ideally, include a test that fails without this PR but passes with it.

Tests and linting

• Run the tests with pnpm test and lint the project with pnpm lint

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[benmccann]

remove prettier from packages, everything runs through the root now (also better aligns with how you work with it in VS Code: no more config duplication needed)
remove eslint from packages, run it once through the root now (revealed some inconsistencies and missing stuff, config tightened up as a result) (bump eslint while we're at it)

Not being able to run prettier and eslint on just the Svelte project has been driving me crazy for two reasons:

• I have to keep switching back and forth between packages/svelte and the root in my terminal since I can only run the command from root now
• I have to wait for them to run over lots of unrelated things like the docs

Is this something we could revisit? I'm also curious what your workflow is like and if there's something more efficient I should be doing. Does prettier work in VS Code now and not before? I've never had it doing anything, but if this fixes it then maybe I don't need to run it on the CLI anymore

[dummdidumm]

I have the monorepo open at the root. prettier then only picks up the .prettierrc at the root, which is why they had to be duplicated before. I don't run eslint much and prettier will auto-format on save so I have no problems with running these scripts from the root.