Asset cutscene two stages

[Xeeynamo]

I completely rewrote the cutscene asset handler. Now instead of parsing the data from the original overlay into a C-like header file, it instead follows a two-stage process. This works by extracting it in asset/ with make extract_assets, to then allow modders to modify the file and build it as a C-like header with make build_assets. This also aims to fix #1701 as the build process takes account of the two-stage process.

I created a framework where each asset type should only make available the two methods Extract and Build. The entire transformation process should be isolated to not create cognitive overload like what we can find in build.go. I would need to migrate all the existing asset types to properly use this new framework. The old code served well enough to understand how to build the entire infrastructure, but it needs to be migrated using the new pattern.

Last, but not least, I renamed config/assets.us.weapon.yaml to config/assets.us.yaml as it is now used by all the overlays