Chainsaw: move loaded assets from loaded_assets to chainsaw_assets for DG

Chainsaw: move loaded assets from loaded_assets to chainsaw_assets so they still work in DG.

Also move unused files to Chainsaw/obsolete folder; they may be deleted in the future if we are sure we don't need them.

We found that some files in src/embedded_assets were automatically copied to bin-release/embedded_assets, but they were not referenced in the source.  After moving them to Chainsaw/obsolete, they were no longer copied to bin-release, but the empty 'embedded_assets' folder was still created.  How to delete it?