[FEATURE] VPK pack assets

[brysondev]

Description

Pack up assets into VPKs to improve performance for lower-end systems.

Proposed Solution

Add VPK packing in github actions.

Alternatives Considered

No response

Additional Context

No response

[blaberry]

Some notes on this:
I think we're better off doing this on the build machine for steam:

1. We don't want to distribute all the ognt assets directly from github
2. The default vpk.exe valve ships is broken (surprise surprise) so doing this at build time will be more annoying than just using the tools available.
3. We're already doing a lot of file-mangling on there that requires various third party utilities, adding another one isn't too much.