fr:861 dynamically build handy models submenu

[ShaneDelmore]

For feature request 861, dynamically build handy models submenu list of models from user resources shape directory, followed by application resources handy_models directory.

This is a simple implementation with no caching and it does not have a gui like prusaslicer shape gallery does for users to add or remove models.

To use add a folder named shapes in your user application data directory and add stl or 3mf files. Underscores in the name will be replaced with spaces when generating the menu entries and the file extension will be discarded.

[ShaneDelmore]

This is targeted at https://github.com/SoftFever/OrcaSlicer/issues/861

[Noisyfox]

Maybe also rename the built-in model file names to make it consistent with current display names? "ksr fdmtest v4" looks much more unpleasing than "Autodesk FDM Test".

[SoftFever]

Thanks Shane. I'm not very comfortable iterating through a folder when a context menu pops up. Plus, the handy_models folder is within the application folder, which is not recommended for storing user content. If you are interested and want to take on the challenge, porting PrusaSlicer's shape gallery would be more preferable. From there, we can further enhance it.

[ShaneDelmore]

I'll close the pr.