popover: Add a Close button to enable us to test unmapping popover
popover: Add a Close button to enable us to test unmapping popover

We'll need this to help us actually fix up x11 grabs

Signed-off-by: Ikey Doherty <d8d992cf0016e35c2a8339d5e7d44bebd12a2d77@solus-project.com>

ikeydoherty/ui-tests,ikeydoherty/ui-tests