Add an option to allow the bottom dock to be full width under the left dock

[metcalfc]

Summary: Sometimes you want more space in the terminal, add a justified alignment option for the terminal panel.

Sometimes you want more space in the terminal. You can close the left dock. But I often still want to see the tree. I'd like an option to expand the terminal (bottom dock) under the left dock. VS Code calls this justified alignment.

https://twitter.com/i/status/1776271247925498277

[mikayla-maki]

Thanks for this feature request! We have a PR up for this feature:

#21337