client side GUI assisted auto completions

[christianparpart]

A little bit of what FinalTerm had been doing.

Warp terminal is IMHO doing it the wrong way of completely taking over the command prompt.
This won't work nicely everywhere and also defeats the strengths of some shells' prompts and their customizability - which also works from remote hosts.

Instead I think VT sequences need to be defined to declare scopes and add new commands/args to the terminal.

[WSLUser]

See microsoft/terminal#6632

Iterm2 already has this and users will probably expect to get the same experience.