Reorganize 3.x branches, repositories and tags

Problem/Motivation

Currently, we have:

• 2 repositories (droopelr & droopler_project)
• 2 locations for droopler repository (drupal.org and GitHub)
• 2 types of tags for 3.3 (8.3.x and 3.x)

In this task, I want to plan how we can make it more simple and more understandable for users.

For Droopler 5.x we will use only 1 repository on drupal.org