e2e CI tests

[arm4b]

The repo should do an end2end test run based on the actual action's Terraform/Ansible code.

We can run a full provision->deploy->destroy pipeline on every PR (it's 10mins). As far as I remember, external collaborators won't be able to run the CI on our behalf so we're good as long as BitOps doesn't leak (#36).

If that feels risky, we can use /commands comments in GH PRs for more granular control the CI runs for testing to avoid overusing the compute resources. Alternatively, use the [ci skip] flags.

Are we confident in our work, ready to dogfood own GH Action and test deploy ST2 instance based on defaults to EC2? This will help verifying the action runs end-to-end on every new feature/change, avoid regressions and also allows testing the changes directly in this repo, rather than using another middle repo, speeding up the development and feedback loop.