git-gui: Clarify the Remote -> Delete... action

Currently, it was not really clear what all does this perform. We rename
"Delete..." to "Delete Branch..." (since this does not delete the remote
as a whole) and relabel the window from "Delete Remote Branch" to "Delete
Branch Remotely" (since the action also involves pushing the delete out).

Signed-off-by: Petr Baudis <petr.baudis@novartis.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

git-gui.sh

@@ -2453,7 +2453,7 @@ if {[is_enabled transport]} {
 		-command do_push_anywhere \
 		-accelerator $M1T-P
 	.mbar.remote add command \
-		-label [mc "Delete..."] \
+		-label [mc "Delete Branch..."] \
 		-command remote_branch_delete::dialog
 }