Use MobileVLCKit / TVVLCKit to implement dialogs properly in external apps

Use VLCKit to implement dialogs properly in external apps

Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

move file inside group

It this flag is set, user interaction will be forced when preparsing the item
given by libvlc_MetaRequest (there won't be user interactions for sub items).

Only callacks are tested by default. In order to test qt dialogs, run the test
manually with './test_src_interface_dialog -a'.