feat: add withCapacity function

[aleclarson]

Summary

This is an alternative implementation of withSemaphore introduced by #331.

It's different in a few notable ways:

• Its name is withCapacity (on the fence about this, but I think it's less jargon-y than withSemaphore and that's probably a good thing)
• It's about 1/3 the size in bytes.
• Different methods
  • No manual acquire/release and I'm leaning toward that being a good thing, though I want to be sure I'm not overlooking an important use case (maybe @hugo082 can clarify this). Side note: Perhaps, in the future, we should consider adding “lower level” (i.e. more error prone, yet more control) variants as class implementations, which might be where the acquire/release paradigm feels more appropriate.
  • Instead of getRunning(): number, there's a hasCapacity(weight?: number): boolean method. I'm not sure what the use case is for getting the current number of locks, so I'm hoping @hugo082 can clarify.

withMutex

This PR doesn't have a withMutex function, and I'm still on the fence about it being a good addition, since it's easy enough to use withCapacity(1, …) for the same behavior? More clarity on this would be great.

Related issue, if any:

#331

For any code change,

• Related documentation has been updated, if needed
• Related tests have been added or updated, if needed
• Related benchmarks have been added or updated, if needed
• Release notes in next-minor.md or next-major.md have been added, if needed

Does this PR introduce a breaking change?

No