Add global items as options for launcher forms

[Bubballoo3]

While global items can be included as default launcher items, they cannot be added to the forms manually, at least through the form editor. While I am wary of the attribute selection becoming too large, I think this could be rectified by adding different buttons for each type of form item. Like 'Add Automatic Option', 'Add predefined option', and 'Add global option'. I could also see it working well even if we combined predefined and global attributes.

Seeing as we eventually want to use the launcher form builder to build batch connect forms as well, this is an essential direction to make this tool complete.