[CI] automatic build runtime docker image

[weimingzha0]

CI should automatically build docker images for HALO:
For Pull-requests, the images are built and tested
For merges, the images will be pushed to container registry.

The version string in tag is determined by git refs:
if the change is on master, the version should be "latest"
if the change is on git tag, the version should be git tag name.
if the change is on git branch, the version should be git branch name.