WidgetOperation configuration- selected project

[NivShalmon]

A WidgetOperation configurations that allows the user to select some projects from his workspace. Should look similar to project->clean->clean projects selected below. What needs to be done is:

1. define how a widgetOperations asks for this kind of configuration in configurationComponents
2. define what information you return to it in register
3. add this configuration to the widget preferences page

This is needed for #1318

[OriRoth]

It can be a simple String in the meanwhile- Project1, Project2, Project3