[FR] Python Security Rules Unit Testing

**Is your feature request related to a problem? Please describe.**
I am using a Python Firebase Functions Backend for My Application but I would like to Unit Test My Firestore Security Rules. There doesn't seem to be a supported library for this in Python.

**Describe the solution you'd like**
Provide a similar library like is provided for NodeJS: https://www.npmjs.com/package/@firebase/rules-unit-testing/v/3.0.2-canary.6d31930b3

**Describe alternatives you've considered**
It may be possible to setup the testing manually without the supported helper methods. I may have to separate my security rules unit testing to another repo and use NodeJS.

The request points to the NodeJS @firebase/rules-unit-testing package as the reference; begin by reviewing that package and the firebase-admin-python repository. Define the Python equivalent's supported Firestore security-rule testing scope, with completion meaning a maintained helper library comparable to the referenced NodeJS package.

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