UX: improve the select template screen in spacetime init

[jdetter]

During spacetime init we're given a screen that lists the available templates that we can select from, or we can paste in a github URL. It would be a lot better if we could just use the up and down arrow keys to select a template and if you don't want to use a template you can choose no template or you can chose "enter a Github URL".

I use this tool locally called ssh-tailscale which displays all of the hosts that I can connect to. This list is quite long:

However, I can start typing to narrow the search:

This sort of UX would be really good here.

Roberto's suggestion: https://docs.rs/inquire/latest/inquire/