mgr/dashboard: Improving the dialog box Titles in Block -> Images
1. In the Images section, if we click on one image and do `Copy RBD` action, the title of the modal says `Copy RBD`. Also if we try to do the same in the Snapshot of the image, the title of that modal also says `Copy RBD`. I think we need to differentiate the title from the Copy RBD action of the image from the Copy RBD action of the snapshot of the image.
2. Also we can improve the title from simply saying Copy RBD to something like `Copy Block Device Image`. There are some suggestions came from our doc team. I'll put that here.
CreateRBD ---> Create Block Device Image
EditRBD ---> Edit Block Device Image
CopyRBD ---> Copy Block Device Image
CreateRBD Snapshot ---> Create Block Device Image Snapshot
RenameRBD Snapshot ---> Rename Block Device Image Snapshot
CloneRBD ---> Clone Block Device Image Snapshot
CopyRBD ---> Copy Block Device Image Snapshot
RBD snapshot rollback ---> Block Device Image Snapshot rollback
Some titles specified in here is lengthy but we can discuss on that.
Reported by the doc team.