Test: Terminal Splitting

[Tyriar]

Refs: #7504

• macOS @ramya-rao-a
• Linux @aeschli
• Windows @egamma

Complexity: 4

It's now possible to split the terminal, the basic features added include:

• "Splitting" the active terminal to the right, you can do this in many different ways:
  • ctrl+shift+5 and ctrl+\ on Windows/Linux
  • ctrl+shift+5 and cmd+\ on Mac
  • Split button in panel actions
  • alt/ctrl+click on + button in panel actions
  • "Terminal: Split Terminal" command
  • An option in right click context menu (note the context menu is disabled on Windows by default, see the terminal.integrated.rightClickBehavior setting)
• The panes rotate automatically when the panel position changes
• Focus can be moved using the keyboard (alt+arrow or cmd+alt+arrow)
• Panes can be individually resized using the mouse or keyboard (ctrl+shift+arrow or ctrl+cmd+arrow)
• Custom size should be retained unless one of the following things happen:
  • A pane is added
  • A pane is removed
  • The panel position is moved