Show 'Source' actions in file explorer context menu

[mjbvz]

Feature request
Show source actions in the file explorer context menu. This would allow triggering actions such as organize imports on file

I believe this would require a new activation event and a new way to present source actions (instead of using the editor right click context menu)

Alternatives

• A generic source context menu could be contributed by an extension

• Or individual extensions could contribute new items to the file explorer context menu

[mjbvz]

A few extensions that implement source code actions use the active text editor, which would means that their actions would not work here:

• Do not use the active text editor for running organize imports code actions vscode-python#2137
• Organize imports code action should not depend on having an active text editor Dart-Code/Dart-Code#1083

[mjbvz]

Needs more thought. We don't have nested context menus in the file explorer currently. It's also not clear how we would activate an extension for this (such as if you click on ts file without ever having started the TS extension previously)

May be better left up to an extension too