Automate release and publish to HashiCorp Registry 

Right now, there are no releases available to be directly used from terraforming, it is necessary to build it from source.

Task:

* [ ] Integrate `openflagr` org with terraform registry
* [ ] Create the private keys to sign the new releases
* [ ] Generate first tag/release with current state
* [ ] Automate the process for every new GitHub release (GitHub actions?)