ActivityShare ui prototype

I prefer to ask for input before getting to far.

We are going to need to distinguish intents from tasker etc., I suggest that we add an extra item to the intent bundle cProvideUi and only show a ui if it is set.

Export doesn't really need a ui because it is so fast. I have added proposed checks, but maybe ActivityMain should just not request a ui.

I don't think old style imports are subjected to the uid check. I think they all get imported.