Create Django Transport

[thuibr]

Add Django ORM transport. This coincides with celery/celery#9500

Django Transport module for kombu.

Kombu transport using Django ORM as the message store.

Features
========
* Type: Virtual
* Supports Direct: Yes
* Supports Topic: Yes
* Supports Fanout: Yes
* Supports Priority: Yes
* Supports TTL: Yes

Connection String
=================

.. code-block::

    django:///

Tested with sqlite and postgres. Also, flower is working reasonably well.

This effort is inspired by Oban for Elixir and River for Go.

[codecov]

Codecov Report

Attention: Patch coverage is 92.37288% with 9 lines in your changes missing coverage. Please review.

Project coverage is 81.50%. Comparing base (a0175b0) to head (321002b).

Files with missing lines	Patch %	Lines
kombu/transport/django/transport.py	90.14%	7 Missing ⚠️
kombu/transport/django/models.py	93.93%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2228      +/-   ##
==========================================
- Coverage   81.50%   81.50%   -0.01%     
==========================================
  Files          77       82       +5     
  Lines        9524     9642     +118     
  Branches     1152     1059      -93     
==========================================
+ Hits         7763     7859      +96     
- Misses       1569     1584      +15     
- Partials      192      199       +7     

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