Feature request: OPA Policy Language

**Is your feature request related to a problem? Please describe.**

OPA is a open source policy engine. It uses a declarative language called Rego.

When writing Rego code, there's a web-based online playground available, that's very useful for testing code.
https://play.openpolicyagent.org/

It's very similar to a Regex engine playground. If you have a section to write your code/rule, a section for INPUT and DATA (additional Data), and a section OUTPUT. You hit run, and the playground gets the input, submit to the opa policy engine (with the rules written) and show the result in OUTPUT section.

I'd like to ask if it's possible to incorporate this functionality (OPA/Rego) in Cyberchef.

**Describe the solution you'd like**

In many companies, the OPA Playground is blocked in web proxy due to security reasons (DLP - as a way to prevent leaking internal data to external sites). Same happens with regex, json converters, and all similar web-sites with these functionalities.

On the opposite site, Cyberchef many times is allowed in corporate network as an internal/deployed/approved tool - for regex, json converters, and etc. So it would be a great addition to the arsenal having OPA incorporated as a feature.

**Describe alternatives you've considered**
Running OPA policy engine locally in the desktop.

**Additional context**
Add any other context or screenshots about the feature request here.