Add "Save" option

[pbking]

Perhaps we could consider a "save" option for the theme. If the current option exports a .zip an additional option could be to "save" the theme where the changes get stored in the theme folder rather than exported as a .zip file.

This would allow the development experience of themes to happen in the FSE and be updated in what is my development environment allowing me to skip the export/unpack/copy/delete process that happens whenever I export the theme.

[MaggieCabrera]

I think this is being discussed to add on core right now too