Change the poll component to by default be able to select a poll in component window properties instead of a folder from which the first poll is used

You can now only use one poll from a folder. It is very confusing imho. If we change

@JcrPath(pickerSelectableNodeTypes = "hippostd:folder")
String getPollDocsPath();

to

@JcrPath(pickerSelectableNodeTypes = "poll:poll")
String getPollDocsPath();

then, by default, a certain poll can be selected. Make sure the code also works with this. Old projects will still have

@JcrPath(pickerSelectableNodeTypes = "hippostd:folder")
String getPollDocsPath();

so the folder picked logic has to stay intact