.github: Added remote execution CI

Summary of changes:

  * .github/compose/ci.remote-execution-cluster.yml

     Added this remote execution cluster definition based on the
     one we were using in gitlab.

     This will bring up an action cache, execution service and storage
     service which can be accessed from outside of the docker on ports
     50051 and 50052.

  * .github/compose/ci.remote-execution-test.yml

    Added this composition which will use host networking more to run the
    remote execution tests adjacent to the cluster, without requiring
    docker-in-docker.

  * .github/workflows/ci.yml

    Added the `remote-execution` job to the main CI, this will
    bring up the cluster, run the tests, and then fetch logs from
    the cluster and bring down the cluster.
3 files changed