workflows: Exclude game libraries from 'content' archive

[res2k]

Don't include game binaries in the "content only" archive, but pull them individually for each platform.
This also means that e.g. Windows only contains the Windows game DLLs.

FWIW, there might be a good reason why the "content only" archives included the game binaries.
If so, maybe it's worthwhile to produce both a "content only" and "content+game" archive?

[darkshade9]

The original purpose for the content-only package was to be used as an all-in-one drop-in mod for anyone who wants to bring their own binary (Yamagi, skuller's q2pro, r1q2, etc..), and to be OS-agnostic. I am not sure how many people actually use this package, but the new Flatpak I'm working on will be using it.

The content+game archives are being generated, the only difference being the game binary packaged with it.

[res2k]

I see. So here's another attempt:
Add a stage that assembles the data only, which is used as input for both the platform-specific binaries as well as "content-only" (which remains an archive consisting of both data and all game libraries).