Implement toggle CLI command for pip and stream bool parameters

[waydabber]

Currently pip and stream can be accessed by set and get but toggle does not work.

[waydabber]

This will toggle PIP on/off:

betterdisplaycli toggle -namelike=gp27 -pip

This will toggle PIP title bar on/off (but won't toggle PIP itself on/off):

betterdisplaycli toggle -namelike=gp27 -pip -showtitlebar

Generally whenever at least one PIP specific togglable bool parameter is present, the CLI will interpret that as the goal of the toggle command, otherwise it will toggle pip itself.