Add support for .svelte files

[stefanmeschke]

Add support for .svelte file extension.

Links: https://svelte.dev/ or https://github.com/sveltejs/svelte

---

$ mdls -name kMDItemContentType -name kMDItemContentTypeTree App.svelte

kMDItemContentType     = "dyn.ah62d4rv4ge81g7xfrv4gn"
kMDItemContentTypeTree = (
    "public.item",
    "dyn.ah62d4rv4ge81g7xfrv4gn",
    "public.data"
)

---

@samuelmeuli Is it possible to test these changes locally? I tried to build it via Xcode, but sadly without any success.

Thanks in advance!

Cheers
Stefan

[samuelmeuli]

Thanks for the PR!

What part of the building process are you facing problems with? I'll try to improve the setup instructions.