[draft] Feat: accesscontrol demo

[xfiderek]

Summary of Changes

This is a draft PR with demo of proposed granular access control model for amundsen.
For more details, please refer to the following slack message [TODO add link]

Tests

Currently only metadata endpoint is tested, as it was only endpoint modified. Classes are not tested yet. After initial approval of the concept, other tests will be implemented

Documentation

There is almost no documentation - refer to slack message linked above

CheckList

Make sure you have checked all steps below to ensure a timely review.

• PR title addresses the issue accurately and concisely. Example: "Updates the version of Flask to v1.0.2"
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• PR includes a summary of changes.
• PR adds unit tests, updates existing unit tests, OR documents why no test additions or modifications are needed.
• In case of new functionality, my PR adds documentation that describes how to use it.
  • All the public functions and the classes in the PR contain docstrings that explain what it does