Feature req: UI adjustments

MacOS Catalina, 10.15.7. Postico 2.0beta (7721).

Two things:

- Id love for the vertical location of the horizontal query window divider (between editor and results) to be sticky. It always resets to a default view where the result grid section is like 25% and the editor 75% and I always almost immediately drag it so it's 50/50. Postico 1 remembered this setting.

- Would love to be able to hide/toggle the Tables/Functions section on the left, so I could just have the Queries window: I rarely use Tables/Functions and the UI would feel cleaner to me if they weren't visible (though a Show/Hide option to return them?)

Thanks!

No files, tests, or entry points are named. Reproduce the layout in Postico 2.0 beta on macOS Catalina, then investigate the UI handling for the editor/results divider and the Tables/Functions section; done means the divider position persists and the section can be shown or hidden.

Written by the indexing model from the issue text.