This commit uses the GitHub Actions cache to ensure that the `rtf`
binary can be re-used between runs if it hasn't changed.
It also caches the linuxkit binaries for use in future stages.
Signed-off-by: Dave Tucker <dave@dtucker.co.uk>
This commit adds a GitHub Actions workflow to replace both CircleCI and
LinuxKit CI.
It will build the Linuxkit binary, run tests and upload artifacts
It replaces the Integration Tests that are run by Linuxkit CI via
the make ci or make ci-pr targets with multiple sets of Integration
Tests that are run in parallel.
It does not yet test GCP. The GCP test in LinuxKit CI could be moved to RTF
Signed-off-by: Dave Tucker <dave@dtucker.co.uk>
