Rename ThreadPool::as_worker() to with_worker()

[BD103]

The docs of ThreadPool::as_worker() describe it as a potentially expensive operation. However, the as_ prefix usually signals a cheap and quick operation (see the Rust API Guidelines and examples such as str::as_bytes() and pointer::as_ref()). This can be a problem, as someone reviewing code may assume as_worker() is a cheap operation and not realize it could cause a mutex lock.

This PR renames as_worker() to with_worker(), in a similar vein to LocalKey::with() and the old TaskPool::with_local_executor(). Not only does the with_ prefix signal that it will pass a worker to a closure, but it also doesn't come with any assumptions on its performance.

This is a breaking change, although I'm not sure how you want to document it.

[NthTensor]

Sweet, thank you so much! I agree, this name is not ideal. I'm still getting the project online a bit, so this will be blocked until I fix CI.

[NthTensor]

CI is now fixed, but I've made some changes to the tests so you will have to rebase.

[BD103]

Ok, it should be all good now! When fixing the conflicts, I ran into this comment:

Forte/src/thread_pool.rs

Lines 633 to 637 in ae7aa8f

	/// Workers are the recommended way to interface with a thread pool. To get
	/// access to worker for a given thread pool, users should call
	/// [`ThreadPool::as_worker`] (which keeps work in the same thread, but
	/// sometimes may fail to acquire a worker) or [`ThreadPool::as_worker`] (which
	/// may send work to other threads, but will always acquire a worker).

Specifically, this bit:

To get access to worker for a given thread pool, users should call ThreadPool::as_worker (which keeps work in the same thread, but sometimes may fail to acquire a worker) or ThreadPool::as_worker (which may send work to other threads, but will always acquire a worker).

I combined it into:

To get access to worker for a given thread pool, users should call ThreadPool::with_worker.

[NthTensor]

Yep, artifact of an older design. I need to do a pass on the docs, there's a few places where I may have left outdated stuff. Thanks for catching that one.