This commit adds the ability to target the first pane in the tree,
always.
I wasn't able to find an existing issue for this, it is just a personal
feature for me. I won't be heartbroken if it does not get merged.
As motivation, I frequently have setups where the thing I am primarily
working on is a large pane on the left and everything else is in smaller
panes positioned elsewhere. I like to have one hotkey where I can go to
any pane and then make it the "primary" pane if I am changing what I am
working on or need to focus on another set of code/documentation/etc.
## Validation Steps Performed
Confirmed that the move focus and swap pane variants both affect the
correct pane.