Migrate Space Agon to OM2 (Running OM2 on GKE)

[peterzhongyi]

This is a follow-up PR that migrate Space Agon from using OM1 to OM2. This PR deploys OM2 on GKE instead of on Cloud Run. Due to limited time, I didn't use helm chart, and simply wrote the om_install.yaml and redis-config.yaml files to deploy OM2.

To run the demo, follow the README until you finished installing Agones. Then to install OM2 to the cluster, in the root directory, first deploy the redis service with

kubectl apply -f redis-config.yaml

and then change the OM_CORE_IMAGE field inside of om_install.yaml to be the OM2 image url - it can either be asia-northeast1-docker.pkg.dev/open-match-dev/open-match/om-core if you have access to the open-match-dev project, or the URL of the OM2 image you build and upload to your own Artifact Registry by following the DEVELOPMENT.md. After changing the OM_CORE_IMAGE field, deploy the OM2 service with

kubectl apply -f om_install.yaml

Then proceed to install the Space Agon game with make build && make install.

[kemurayama]

@peterzhongyi

Thank you for the PR on Space Agon. My apologies for the delay in reviewing. I've just tested it locally and it works perfectly. I'll merge it now.

[kemurayama]

LGTM. Confirmed it worked on GKE Cluster