feat: Regal integration

[cpmachado]

Went searching for some tooling around Rego.
I found:

• OPA cli: https://www.openpolicyagent.org/docs/latest/cli/
  • It's the cli you are probably familiar with, which has a format function via opa fmt
• Regal: https://github.com/StyraInc/regal
  • It's a linter for Rego, which appears to be worth it.

I integrated this Regal tool into this branch github action and fixed the reported errors.

[cpmachado]

On another note, please don't merge it straight, but squash merge it please as you see fit. :-)