feat(worker): support dynamic worker option fields

[jamsinclair]

Description

The Problem

Vite has a hard requirement that worker options are defined statically or it throws an error. This prevents some legitimate use cases, such as when a dynamic name is used to differentiate workers. As seen in the Emscripten project (code reference)

worker = new Worker(new URL('target.js', import.meta.url), {
  'type': 'module',
  'name': 'em-pthread-' + PThread.nextWorkerID,
})

This is causing some issues in trying to update Emscripten to support Vite when workers are in use.

Solution

Vite only needs to ensure that the type value is statically defined. Other fields could be dynamically computed with no effect on the Vite bundling process.

A side discussion was started in #18396 (comment) about relaxing the usage of some worker option fields to support this.

This PR hopes to solve this issue in a backwards compatible way that still ensures that Vite can have high confidence in asserting the worker type at compile time.

[jamsinclair]

Looks like this change broke the tests in two ways 😅

• Windows paths aren't resolving nicely with the unit tests (Edit: this was caused by a bug in the plugin)
• It seems to have broken the worker integration tests Solved by 7cf1551

I'll look into fixing these tomorrow.

[sapphi-red]

Thank you! I left some minor comments.