feat: searched params attached to workers are now preserved

[jurerotar]

This PR adds support for preserving search params passed to workers. This means that user-provided search params are now appended next to vite-generated ones.

The reason we need this functionality is because we currently have a blocker in sqlite-wasm repository related to this. The short version is that certain database features rely on passing search params to workers on initialization. These search params are currently stripped.

You can find a more in-depth explanation of the issue we're attempting to resolve in this comment.

[sapphi-red]

switch(vfsName){
  case 'opfs':
    return new Worker(new URL("sqlite3-opfs-async-proxy.js?vfs=opfs", import.meta.url));
  case 'opfs-wl':
    return new Worker(new URL("sqlite3-opfs-async-proxy.js?vfs=opfs-wl", import.meta.url));
}

To confirm, is this what you have in the source code? Is the expected build output to be like the following?

switch(vfsName){
  case 'opfs':
    return new Worker(new URL("path-to-sqlite-worker.js?vfs=opfs", import.meta.url));
  case 'opfs-wl':
    return new Worker(new URL("path-to-sqlite-worker.js?vfs=opfs-wl", import.meta.url));
}

[jurerotar]

To confirm, is this what you have in the source code? Is the expected build output to be like the following?

Correct! The worker internally relies on vfs search param being passed to it. Because it was getting stripped during bundling, our tests failed.

Since this PR was raised, we have managed to find a workaround. It currently works like this:

const url = new URL('sqlite3-opfs-async-proxy.js', import.meta.url);
url.searchParams.set('vfs', vfsName);
return new Worker(url.toString());

vfs param is now correctly preserved. I am not sure if this is the intended way of passing search params to workers, but if it is, I'd be happy to document this in the docs instead 😄