Create new API keys from doctl

**What is the problem this feature would solve? Please describe.**
It would be great if I could create a new API key with `doctl`. Using the web interface is very slow, as I usually end up on digitalocean.com, find the sign in button, then click through to my account, re-authenticate, create a new key, and then find the shell where I wanted to use it.

**Describe the solution you'd like**
Ideally, I could run `doctl account key new [-rw] [label]`, complete a second factor in a new browser window or even within the terminal, and be given a new API key. I could also run `doctl account key revoke [keyid]` to delete the key later

**Additional context**
With [go-libfido2](https://github.com/keys-pub/go-libfido2), I could use my yubikey from the command line to provide a second factor