refactor: asyncio, ssh-cli, AsyncSSH, AsyncContext

[JakkuSakura]

• Pull request is based on the default branch (3.x at this time)
• A 4.x branch should be created
• Pull request includes tests for any new/updated operations/facts
• Pull request includes documentation for any new/updated operations/facts
• Tests pass (see scripts/dev-test.sh)
• Type checking & code style passes (see scripts/dev-lint.sh)
• Feature parity of old version
• Verified code compatibility with 3.x
• AsyncContext fully implemented

closes #1478

closes #1474

[Fizzadar]

Wow! This is incredible work, @JakkuSakura. I think moving to asyncio is definitely the way forward - I actually think we should make pyinfra's API async only and remove the complexity of having the two context types.

I still need to read through the PR in full, but generally this looks amazing, nice that the API changes aren't actually too crazy. I'd like to figure out how we can make the API accessible with minimal boilerplate, I think this is possible if we go all async.

Going to reach out (email) to figure out how we can best land this (and 4.x).

[JakkuSakura]

Glad to hear this. I'm going to use this branch in my own project to see if it causes any issues

[JakkuSakura]

I've been using it for a while without issues. Any chance of merging it?

[Dexmachi]

What is the current situation for this PR?

[Fizzadar]

Current state of PR: this is a huge undertaking and breaking change, so this is effectively v4 development right now, with no timeline for release as of yet.