Refactor: using task object instead of dict, removing queues to avoid blocking and reorganization of files

[GDay]

This is still very much a work in progress! Just saving this here as a draft to track progress. It's pretty much a full rewrite of the library. There is still a lot to do. What has been done so far:

• Restructured the app into multiple files, to clean up the cluster.py file
• Replaced shared queues with pipes, which will resolve the blocking issue when a process crashes (fixes #23)
• Changed the task dict that gets passed through the cluster to a dedicated dataclass, so every task is now an object instead of a dictionary.
• Task timeouts are now properly caught

It's currently functional for normal async tasks, the rest is still buggy.

What still needs to be done:

• [x] Fix the scheduling
• [ ] Redo all tests (basically full rewrite of the test suite)
• [x] Clean up and change wording of some functions/variables
• [x] Re-implement monitoring management commands
• [ ] Probably fixing more things that I will find along the way
• [ ] Check for breaking changes moving to this version (no breaking changes so far)

Since this is a very heavy rewrite, this will need a lot of eyes before this can be merged (we are not there yet anyway).

[coveralls]

Pull Request Test Coverage Report for Build 4673412590

• 588 of 1042 (56.43%) changed or added relevant lines in 21 files are covered.
• 230 unchanged lines in 14 files lost coverage.
• Overall coverage decreased (-16.9%) to 73.182%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
django_q/exceptions.py	16	17	94.12%
django_q/status.py	0	1	0.0%
django_q/utils.py	5	6	83.33%
django_q/helpers.py	27	34	79.41%
django_q/models.py	23	31	74.19%
django_q/tests/test_cluster.py	66	74	89.19%
django_q/queue_task.py	119	129	92.25%
django_q/management/commands/qinfo.py	38	55	69.09%
django_q/scheduler.py	54	75	72.0%
django_q/process_manager.py	34	57	59.65%
<!--	Total:	588	1042

Files with Coverage Reduction	New Missed Lines	%
django_q/brokers/init.py	1	89.25%
django_q/core_signing.py	1	80.85%
django_q/monitor.py	1	50.72%
django_q/tests/testing_utilities/multiple_database_routers.py	1	64.71%
django_q/conf.py	2	67.91%
django_q/brokers/redis_broker.py	3	90.2%
django_q/tests/test_commands.py	3	84.21%
django_q/management/commands/qmonitor.py	7	0%
django_q/management/commands/qmemory.py	8	0%
django_q/tests/test_cluster.py	25	90.88%
<!--	Total:	230

Totals
Change from base Build 4589544429:	-16.9%
Covered Lines:	2636
Relevant Lines:	3602

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💛 - Coveralls