feat: Svelte adapter

[david-roeger]

This PR:

• Adds initial implementation of the Svelte adapter
• Adds initial tests for the Solid adapter

Regarding the questions in the issue:

1. Packaging - I switched from tsub to svelte-package the official svelte way of well building packages. The build output from tsub threw errors when I tried to use it.
2. Testing - I used testing-library svelte version. (The test for counting the rerender is a bit ugly because of onMount isn't called when rendering components  testing-library/svelte-testing-library#222)
3. Reactivity interop - since svelte offers native store support this is quite nice. For the Api surface I tried to stay as close to the other packages.

Note: I just copy and pasted the shallow function - it might be worth refactoring that into the core package?

Closes #4

[david-roeger]

For the setup of the whole package I mainly copied and pasted from the vue example and svelte-query. I hope the setup is fine.

[crutchcorn]

This looks great to me, but I'm not a Svelte-spert admittedly 😅

Tagging in @LukeHagar to review the Svelte code, as he was offering to help out with a Svelte adapter for Forms

PS I'm so sorry I missed this PR - I just didn't see it at the time; no excuses. Sorry!

[LukeHagar]

I just wanted to follow up here, this looks like a good implementation, and I'm glad to see you using the existing Svelte store functions.

That being said I think this will end up changing once runes come about.

[david-roeger]

@LukeHagar That's what we talked about yesterday in the discord. I played a bit around with runes and that's what I got so far:
See david-roeger#1
Or in the repl

But the tooling around svelte-5 is... well not there yet and I can't get svelte-package to output types for index.svelte.ts files or tests working

@crutchcorn does it make sense to release the adapter in it's current form for svelte-4 or should we just wait until svelte-5 arrives?

[crutchcorn]

Let's hold off for Svelte 5 - apologies for sending us all down this goose chase until then 😅😅

[david-roeger]

Hey there,
with Svelte 5 now being in Release Candidate Stage I would be like to continue working on the adapter :)

[LukeHagar]

Sounds great to me!