Audit and cleanup named commands exposed by GitHub for Visual Studio

[jcansdale]

Extensions can expose named Visual Studio commands. They are useful and important for a number of reasons.

1. Power users like to use them for binding keyboard shortcuts
2. They can be used to simplify automation testing
3. The commands an extension exposes can act as a summary of what it can do

It currently isn't easy to find the commands GitHub for Visual Studio exposes. A search using Command Bar > Customize... > Keyboard... only reveals the following:

There are more commands hidden away.

A more extensive search shows up the following, which don't contain "GitHub" and are pretty much impossible to find:

EditorContextMenus.CodeWindow.OpenFileinSolution
Edit.NextComment
Edit.PreviousComment