General redesign/refactoring

[DanielePalaia]

Scope of this PR is to make some improvements to this script.

• Poetry is now integrated in order to organize the script as a proper project
• Some unit tests to validate the operators bundles are now integrated to the project
• A github action that run the tests on PR/commits and do some formatting checks (isort/black) has been integrated
• The script now support air grapped installation as for: https://github.com/rabbitmq/OLM-Package-Repo/issues/5

Some refactoring:

• We have now just one script for the two operators: the script is automatically able from the manifest to dectect if it is a cluster operator or topology operator manifest
• The single-active consumer related code has been removed has this operator is not supported anymore
• Clean up of some useless files that were in the generator folder creating confusion
• Better management of the "replace" field (The script check what is the last release operators) without specifying it in the replace.txt file as it was done before
• The code is formatted with isort and black tools in order to have a proper uniform formatting in the project / using logging instead of printf
• The README has been updated and a license file provided

[DanielePalaia]

I'm integrating this one at the moment in order to test all the reworking on the next operators releases and start new improvements from this base!