feat: expose event.route and event.url to remote functions

[Rich-Harris]

We originally chose to omit event.route and event.url from remote functions, because we worried that it could create confusion — if a query's return value is based on event.url, it could become incorrect later when the URL changes and the query result doesn't.

But it's too restrictive. It's often necessary to know which page a remote function was called from. For example if a query redirects to a /login page, it's nice to be able to include a redirectTo parameter, and for that you need to know the page the user was trying to access:

if (!user) {
  redirect(307, `/login?redirectTo=${encodeURIComponent(event.url.pathname)}`);
}

This PR makes that possible. Closes #14543.

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[PatrickG]

Should we add a note in the docs that you can not "trust" event.url/event.route if event.isRemoteRequest is true?
Otherwise I can see people trying to secure their remote functions in the handle hook with it.

[benmccann]

This is the line causing the lint failure:

packages/kit/test/apps/basics check: /home/runner/work/kit/kit/packages/kit/test/apps/basics/src/routes/remote/event/+page.svelte:4:16
packages/kit/test/apps/basics check: Error: 'await' expressions are only allowed within async functions and at the top levels of modules. (js)

[Rich-Harris]

uhhhhh how do we fix that? does svelte-check need to be updated?

[Rich-Harris]

(I also get red squigglies in my editor, which I assume is because the VS Code extension is attempting to load config from the project root, rather than the nearest svelte.config.js to the file in question. Is this a bug @dummdidumm?)

[Rich-Harris]

Ok, so it turns out enabling async rendering breaks a few tests, which we'll have to look into. Disabled it for now

[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-14606-svelte.vercel.app/

[Rich-Harris]

Should we add a note in the docs

Yeah, just pushed something. I do almost wonder if we should just automatically re-run queries that depend on these values when they change, because I can see people doing that regardless