Profile Switcher QOL improvements

[TheBigWazz]

Some Quality of Life improvements I'm suggesting for the Profile Switcher:

• Dynamically set the switcher browser pop-up background color and text to match the current theme values
• Add Keyboard shortcut for Launching / Focusing a profile.
• Set toolbar icon to current moz-profile icon

I tried setting the profile switcher pop up menu color manually through userChrome.css but I don't know enough about html and selectors to get it working. If it's possible to target the HTML background somehow, could someone drop a comment?