- Add `parent` and `child` movement directions to move up and down the tree respectively
- When a parent pane is selected it will have borders all around it in addition to any borders the children have.
- Fix focus, swap, split, zoom, and move to all handle interacting with more than one pane.
- This technically leaves control focus on the first control in the focused subtree because panes aren't proper controls themselves.

…the parent. this allows us to maintain focus on the correct terminal and also go back down the correct path with the child navigation.

… change always occurs.

…t overwrite them if the two parents are related.

…t-subtree-panes

 Conflicts:
	src/cascadia/TerminalApp/Pane.cpp
	src/cascadia/TerminalApp/TerminalTab.cpp

- font size changing, closing, read-only, clear buffer, changing color scheme all updated for parent panes
- Make the WalkTree function more ergonomic to use, so in the default case you don't have to return a bool

… pane when a parent is focused

…s in a (parent) pane.

- Switch to keeping a path of panes instead of a direct pointer, and update
  that on close.
- Make sure that we focus a terminal after close.
- Also update the tab active pane information on close in case a child of
  the focused pane closed, since the GotFocus handler will rightfully ignore
  that the same pane is getting focused again (but still information about it
  changed).
- Add TODO on previewing color schemes.

…d that would cause the correct focus to be lost.

…ccessfully

…is broken on unfocused terminals.

…we dont lose context when we swap panes.

…t-subtree-panes

 Conflicts:
	src/cascadia/TerminalApp/Pane.cpp

…otherwise they hold onto buffer references that break resizing