Add shortcut keys for function keys #514
Description
I installed radian and started using with vscode yesterday. It's a huge improvement after some tweaking of setup. So, big thanks to all who have worked on it. However, one thing I still miss: I want to be able to use F1 to open documentation for a function, or F2 so see its implementation like I can with Rstudio. It also work if vscode support this, but I haven't figured it out. Implementing in radian make it independent of the IDE/editor, that is also nice.