Show "Exit back to side panel" in options status bar for focused main view

It's maybe not totally obvious, so let's show it.

Esc now appears twice in the status bar, because the global controller also
appends its generic "Cancel". We'll fix this in the next commit.

pkg/gui/controllers/main_view_controller.go

@@ -39,9 +39,10 @@ func (self *MainViewController) GetKeybindings(opts types.KeybindingsOpts) []*ty
 			DisplayOnScreen: true,
 		},
 		{
-			Key:         opts.GetKey(opts.Config.Universal.Return),
-			Handler:     self.escape,
-			Description: self.c.Tr.ExitFocusedMainView,
+			Key:             opts.GetKey(opts.Config.Universal.Return),
+			Handler:         self.escape,
+			Description:     self.c.Tr.ExitFocusedMainView,
+			DisplayOnScreen: true,
 		},
 		{
 			// overriding this because we want to read all of the task's output before we start searching