keyboard support: [tab] and overlays

[ccoenen]

Which part of the project should be enhanced?

The Editor

Is your enhancement request related to a problem? Please describe.

(this was originally a suggestion by Scott Mattan on our matrix channel, which I'm conserving here)

It might apply to more than just emoji, but when you have a partial insert it brings up a menu. When that menu comes up its intuitive to be able to tab complete, but tabbing here inserts a tab character at the head of the current line.

hedgedoc-tab-emoji.mp4

Describe the solution you'd like

I would expect tab to cycle through the options and enter to confirm/auto-complete while a menu is open.

Describe alternatives you've considered

(does not apply)

Additional context

No response