vim: Add keybindings for resizing docks

[AidanV]

Closes #23334

This does not follow the exact way that windows are resized in vim. Normally the command is ctrl-w > however this PR uses just ctrl->. This is because I could not find a good way to read in a count like 10 ctrl-w ctrl->. This is not really a problem since ctrl-> can be held down, which, in my opinion, speeds up resizing. I think this is a good compromise since it improves usability; however, I am concerned that this is not intuitive. I am looking forward to feedback.

Release Notes:

• vim: Fixed ctrl-{<,>,+,-} for resizing docks in addition to panes

[ConradIrwin]

Nice! Thank you for this!

I don't think we need to support resizing a panel you're not focused in, so I think we only need one action; and we should do the right thing depending on which dock is focused. (see here for an example of that)

It's probably easiest to re-use the existing vim::ResizePane action (even though I know these are not panes) in the same way we do for ActivatePaneInDirection, so we should be able to merge this code into the existing handler for that and leave the keybindings as is.

(Although I like the idea of having it bound to something repeatable, it seems best to have it work with what people already know from vim)

[ConradIrwin]

Perfect, thank you!