Build Linux Game Client in Cloud Build

[markmandel]

Since we're building the dedicated game server - we could also build the client and stick it in a storage bucket somewhere.

Unfortunately we can only build the Linux client, since cross compilation from only works on Windows (and doesn't support Mac either), but it's at least a nice start.

[markmandel]

Started work on this.

[markmandel]

Just tracking some resources that are useful:

• https://unrealcontainers.com/docs/use-cases/continuous-integration#building-and-packaging
• https://docs.unrealengine.com/5.2/en-US/build-operations-cooking-packaging-deploying-and-running-projects-in-unreal-engine/ (shows you how to automate creation of the RunUAT command))
• https://docs.unrealengine.com/5.2/en-US/quick-start-guide-for-using-container-images-in-unreal-engine/

[markmandel]

Just as a note as well - will also want to build the frontend client while we are at it.

[markmandel]

Okay, got a Linux build working via the Container Image... but it's not Cooked, so working out which step I missed.