Draft: POC: Focus Mode

What does this MR do and why?

WIP

TODO

1. Add description for quick access (expandable widget on top)
2. Move file tree to quick access (show on click only)
3. (potentially) Always switch to Show one file at a time mode

Screenshots or screen recordings

Default mode	Focus mode

How to set up and validate locally

1. Open any MR
2. Hit F on your keyboard

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.