[darktable] Allow reuse of retouch module shapes as masks in other modules

Darktable 5.2.1 Duplicate of #10336 **Is your feature request related to a problem? Please describe.** Reuse of masks over all modules should be possible to increase usability. Create a mask in module A, reuse the same mask in module B. Or create a copy of the original mask and reuse it in module B. My use case (when I stumbled upon this): I added a fill color mask in the retouch module and wanted to add grain to the same area to let it blend in better. I had to redraw the mask in the grain module. Reusing a mask via the maskmanager would've been much easier. It is not transparent for the user why some masks are in the mask manager and other aren't. **Describe the solution you'd like** Make all masks available in the mask manager to make mask usage uniform in the application. **Alternatives** ? The comment of @TurboGit was > That's expected. The forms in Retouch module (and it was also the case for the now deprecated spot removal) are not part of the mask manager. It is also the