Improve keybinding descriptions

This adds a bunch of tooltips to keybindings and updates some keybinding descriptions (i.e. labels).

It's in preparation for displaying more keybindings on-screen (in the bottom right of the screen),
and so due in part to laziness it shortens some descriptions so that we don't need to manage both
a short and long description (for on-screen vs in-menu). Nonetheless I've added a ShortDescription
field for when we do want to have both a short and long description.

You'll notice that some keybindings I deemed unworthy of the options view have longer descriptions,
because I could get away with it.

pkg/gui/controllers/sync_controller.go

@@ -35,12 +35,14 @@ func (self *SyncController) GetKeybindings(opts types.KeybindingsOpts) []*types.
 			Handler:           opts.Guards.NoPopupPanel(self.HandlePush),
 			GetDisabledReason: self.getDisabledReasonForPushOrPull,
 			Description:       self.c.Tr.Push,
+			Tooltip:           self.c.Tr.PushTooltip,
 		},
 		{
 			Key:               opts.GetKey(opts.Config.Universal.Pull),
 			Handler:           opts.Guards.NoPopupPanel(self.HandlePull),
 			GetDisabledReason: self.getDisabledReasonForPushOrPull,
 			Description:       self.c.Tr.Pull,
+			Tooltip:           self.c.Tr.PullTooltip,
 		},
 	}