Run `bazel test` automatically in CI?

[RRobot-lm]

Currently there does not seem to be an automated CI execution to the code under test/. Is the concern that it takes too long to compile?

[spacewander]

Envoy uses Google's service as its remote cache in the CI: https://github.com/envoyproxy/envoy/blob/3bcac8143b2dc39bf42ec0faed79e491cfe7efe7/.azure-pipelines/pipelines.yml#L138

Maybe we can use GitHub's cache action to reduce build time?

[doujiang24]

@RRobot-lm Yeah, the runner of GitHub action is too weak.

Build takes 4+ hours and Test failures after 5+ hours. https://github.com/mosn/envoy-go-extension/actions/runs/3399605971

[doujiang24]

@spacewander Yeah, cache is worth a try.