add svelte support

[KraXen72]

svelte is another popular UI framework similar to react.
being able to see lint errors in <script> and <script lang="ts"> would be a great start, and later even in inline-expressions & more with proper svelte file parsing

there is currently only: https://github.com/sveltejs/eslint-plugin-svelte, which uses https://github.com/sveltejs/svelte-eslint-parser
eslint is generally very slow for me and that's why i use quick-lint-js.

this feature would improve my life a lot.

[strager]

Svelte support is a great idea! Your suggestion is similar to #116, but Svelte has its own syntax as you mentioned.

Unfortunately, because TypeScript support is more urgent right now, I won't implement this feature soon.