[bld] Add automated packing of the mod + assets for each platform into `mod-longname-v0.0.0.zip` for distribution builds

[heysokam]

• [x] #68
• [x] #70
• [x] Successfully creates versioned .zip files inside the bin/releases versioned subfolders https://github.com/OpenQuake3/defrag/commit/19b8bfe2d17dc996561fdc46485f61f03c122ae8

[heysokam]

Completed with https://github.com/OpenQuake3/defrag/commit/19b8bfe2d17dc996561fdc46485f61f03c122ae8