Add commands shortcuts

[thedemons]

Due to a large number of key combinations in Visual Studio are already taken, I've decided that all shortcuts related to Codeium should be prefixed with ALT+C

• ALT+C ALT+C: Open chat window
• ALT+C ALT+E: Explain code block
• ALT+C ALT+R: Refactor function

Deciding the key combination is not easy, as it greatly impacts users' workflow. The considerations that led to this decision were:

• The ALT+C prefix combination is not used by default and rarely used by other extensions. It also stands for Codeium.
• The most used command is Open chat window, which was set to ALT+C ALT+C so that the users could hold ALT and press C twice for convenience.
• The C, E, and R could be pressed easily using one (left) hand instead of requiring both hands.

[fortenforge]

God Visual Studio is just the best IDE