This is built to test the following assumptions:
1. We can trigger a GitHub action event on the changing of a
file/directory.
2. We can use GitHub actions to build a docker image.
3. We can use GitHub actions to push a docker image to a container
registry.
4. We can use GitHub's container registry.
Right now this will only build and push ubuntu-20.04_all-depenencies, as
a test.
Change-Id: Ie1a55c97c6eef26281456c908e1200b27da4d961
7cdce3a975