Provide option for panel sizing to be percentage-based instead of pixel-based

[candelabrapink]

Related to #1317887079 in the vscode repo.

It would be nice if an option were given to use percentage-based panel resizing instead of pixel-based. I use Positron on multiple screens, and when switching between a laptop display and a larger monitor, panel sizing retains pixel height instead of being percentage based. Because my MacBook has a higher ppi than my monitor, the difference is exaggerated, especially when in fullscreen.

On a 27" 108 ppi screen:

And on a 14.2" 254 ppi screen (2x scaling, since it's a Retina-type display), without rearrangement:

If I have the bottom panel at half-height on the 27" screen, it gladly takes up the entire center area of the screen without rescaling. Thoughts?

[juliasilge]

Thank you for this feedback! We haven't invested in really fundamental layout UI changes like this so far; we prioritize our time/effort on features that are about data science work specifically and largely accept how things work upstream in code-oss for features that anyone who writes code needs (version control, editing a file, etc). However, I see what you are saying! Let's use this discussion to gather input on how important this might be for our users.