feat(cli/repl) add tab completion

[caspervonb]

This adds tab completion for global identifiers and object properties.

Closes #3086

[caspervonb]

Make this a stream and select on it below.

[caspervonb]

Alright so right the first pass only supports a few simple scenarios single line scenarios

Deno.|<tab>
Deno.write|<tab>
Deno[|<tab>
Deno["write|<tab>

Next step would be for completions for multi-line "lines" based on the current cursor position

const foo = Deno.|<tab>
(
  Deno.write<tab>
)
false, Deno[<tab>
true && Deno["write<tab>

And also add support for identifier completions

De|<tab>
let foo = win|<tab>
(
  con|<tab>
)

[ry]

Tested it locally - seems to work! Very nice.

It only works for Deno.|<tab> tho. When I do windo|<tab> it doesn't complete to "window".

[caspervonb]

. When I do windo| it doesn't complete to "window".

Yet to be implemented, only the rhs of propery accessors are completed at the moment 🙃

[bartlomieju]

@caspervonb please rebase

[caspervonb]

Will do, merge #7896 before this one please (it's freshly rebased) 🙃

[bartlomieju]

LGTM, very cool feature 🚀

In future we should consider changing colors a bit for autocompleted items or even displaying list of all possible suggestions.

[caspervonb]

There are other completion modes available, specifically there's a list list-mode that interoperates with "hints" (the one trait we haven't touched on yet in rustyline).

So yeah that's open ended and should be relatively accessible for tweaking 🎉 .