[Select tool] Intersect and exclude should show previous selection
Description Currently, we can't see the previous selection used for the intersect calculation, degrading the UX and increasing guesswork.
https://github.com/user-attachments/assets/57033e26-7a68-45c3-ab99-b451004d537d
Maybe we could have another selection being shown with a different color, or something similar.
Testing in Paint.NET it shows an outline of the original selection so that you can still see it
https://github.com/user-attachments/assets/1af3422f-c1b7-4cd0-83e0-1e28f20c0145
Testing in Paint.NET it shows an outline of the original selection so that you can still see it Screen.Recording.2025-05-15.at.12.02.29.AM.mp4
Probably would be good to also show the outline in exclude as well then, for consistency.
Btw, Paintdotnet's moving dotted outline is pretty neat. Maybe we should bring something similar at some moment.
I'll work on this.