Add Vim keybindings to Web IDE

Problem to solve

Make the Web IDE friendlier and faster to use with Vim keybindings ⌨

Further details

Add Vim keybindings to Web IDE editor

Proposal

:wq

What does success look like, and how can we measure that?

Vim mode implemented in Web IDE

Links / references

https://docs.gitlab.com/ee/user/project/web_ide/#comment-3864417729