Allow typescript configuration files

[ecstrema]

This PR adds the possibility to use typescript configuration files, and makes use of this in the docs website.

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests

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

Changesets

• If your PR makes a change that should be noted in one or more packages' changelogs, generate a changeset by running pnpx changeset and following the prompts. All changesets should be patch until SvelteKit 1.0

[changeset-bot]

🦋 Changeset detected

Latest commit: 537c2a7

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@sveltejs/kit	Patch
kit.svelte.dev	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[bluwy]

We just had a similar PR #4031 a while ago and got closed because we want to resort to sveltejs/rfcs#59 moving forward. Further reasons are noted at #4031 (comment), so unfortunately this won't likely be merged.

[ecstrema]

ahh too bad.

[ecstrema]

I am reopening, because this PR introduces none of the problems in the discussion you linked above.

Except for using an external package. However, it works perfectly.

[bluwy]

It introduces compatibility issues with language tools and vite-plugin-svelte no? They can't load svelte config in typescript.

[ecstrema]

Not that I can see...

EDIT: actually yes, it does, see my next comment

[ecstrema]

so vite plugins and aliases are not found.

[ecstrema]

I guess I just didn't look close enough.

[ecstrema]

Still I believe that updating accordingly the language tools shouldn't be that much of a deal