CodeWhisperer requires IntelliCode to be installed?

When I first installed the extension I could authenticate but CodeWhisperer was not working at all and the "brain" icon at the bottom didn't show up neither did pressing `Alt+C` do anything (except a system *beep*). After some fiddling and head scratching I reviewed the installed components in the installer and noticed that IntelliCode was not installed. CodeWhisperer worked after I installed it. I'm using Visual Studio 2022 version 17.9.6, by the way.

Does the extension rely on IntelliCode being installed? If it does it would be helpful to mention it in the docs/getting started guide, so that other unfortunate souls don't waste as much time as I did :)

Start with the docs/getting started guide and verify the reported behavior in Visual Studio 2022 version 17.9.6, comparing an installation with and without IntelliCode. Confirm whether IntelliCode is required for CodeWhisperer, then document the prerequisite and installation steps if the dependency is reproducible.

Written by the indexing model from the issue text.