Install script should be able to install remotely

[nhooyr]

Waiting on #1701 to be merged, then fix any release blocking bugs and release the next release and then I'll do this to deprecate sshcode.

Also see coder/sshcode#185

[nhooyr]

- [ ] support for hosts without internet

• support for non ssh shells

[nhooyr]

See #2183 and #2219