Set the mouse cursor in the canvas based on the current tool and its state (#480)

* Add FrontendMouseCursor and DisplayMouseCursor

* Add update_cursor method to the Fsm trait and implement it for all tools

* Rename DisplayMouseCursor to UpdateMouseCursor

* Add 'To CSS Cursor Property' transform decorator and change the mouse cursor in the canvas based on the current tool and its state

* Implement update_cursor for Navigate tool properly

* Keep the cursor when dragging outside of the canvas

* Change the mouse cursor to 'zoom-in' when LMB dragging on canvas with Navigate tool

* Rename FrontendMouseCursor to MouseCursorIcon

* Rename 'event' to 'e' and replace v-on with @

* Change the definition of the MouseCursorIcon type in TS

* Replace switch with dictionary look-up

* Move the definition of MouseCursorIcon closer to where it's used

editor/src/viewport_tools/tool.rs

@@ -27,6 +27,7 @@ pub trait Fsm {
 	) -> Self;
 
 	fn update_hints(&self, responses: &mut VecDeque<Message>);
+	fn update_cursor(&self, responses: &mut VecDeque<Message>);
 }
 
 #[derive(Debug, Clone)]