fix(sveltekit): Wrap load when typed explicitly

[sreetamdas]

• When load is explicitly typed (using LayoutLoad, PageLoad, etc.), auto-instrumentation fails.
• The SvelteKit docs suggest using the satisfies operator everywhere, but this is not strictly enforced. Prior to support for satisfies in TypeScript 4.9, the docs also suggested using explicit types, and were updated once support was more common. (PR)
• Update the hasLoadDeclaration regex introduced in feat(sveltekit): Auto-wrap load functions with proxy module #7994 to also check for cases when there is an explicit type.
• Simplified example of a +layout.tsfile that would be skipped:

   import type { LayoutLoad } from "./$types";
   export const load : LayoutLoad = async () => { return { props: { msg: "hi" } } }
   
   // message when debugging: 
   // Skipping wrapping /src/routes/nested/+layout.ts because it doesn't declare a `load` function

---

Before submitting a pull request, please take a look at our Contributing guidelines and verify:

• If you've added code that should be tested, please add tests.
• Ensure your code lints and the test suite passes (yarn lint) & (yarn test).

[Lms24]

Hi @sreetamdas thanks for opening this PR! You're absolutely right, I missed this case.
I'm going to merge this PR to unblock folks using explicit typing. In the long run, though, I think we need to replace this regex with an AST check.

[sreetamdas]

@Lms24 Thanks! And yep, understood. I'll keep an eye out when you implement it, I'd love to see how that works. 😄

[Lms24]

Expect this to be released on Monday :)