Don't use semaphores for blocking

[davedelong]

Generally, mixing semaphores and async is a risky proposition.

This PR changes every ParsableCommand to be an AsyncParsableCommand, so they have a run() async method instead of a run() method. This means we can trivially replace the usages of DispatchSemaphore with the async versions that are created automatically by the compiler when importing closure-based methods. (Under the hood they use continuations)

I decided to change every ParsableCommand to be Async, even though it was only needed for Manage and Set. This ensures consistency between command definitions and easier async adoption in future PRs.

[scriptingosx]

oh excellent catch, I have been dragging that code with the semaphores around for too long.

Question: is there a reason you are declaring all commands as asynchronous in stead of just the few that actually call the methods you have changed to async?

[scriptingosx]

Ignore the question, you did answer that...

[scriptingosx]

thank you!