Worker & worker_threads stability tracking issue

[Jarred-Sumner]

Worker in Bun is still marked as experimental. There are many different issues related to this.

TODO:

• Bun leaks memory in Workers #5709
• Make all usages of *JSC.EventLoop use a weak pointer or an integer for the ScriptExecutionContextID, so that we do not attempt to reference an event loop of a closed Worker
• Have an easy way to force the closing state of all I/O related resources in Bun, so that writing tests for this stuff is trivial
• Ensure NAPI finalizers are handled correctly