Need to have UI indication that the window was launched elevated.

Issue #632 makes it clear the reason why it's not a good idea to mix elevated/non-elevated tabs, but if you launch a new Terminal using "Run as administrator", there is no indication in the UI that the tabs are running elevated.

Proposed technical implementation details (optional)

Add settings for a separate profile background colour, background image, and ideally title bar differences to be applied when the window in running elevated.