PR change pass.

[sbSteveK]

Changes:

• Remove two mutex locks and use a singular lock to reduce probability of deadlocks and simplify logic around shared data between threads.
• Shutdown/cleanup restructure
• Added storage of parent elg to aws_dispatch_loop.
• More error reporting and logging for clarity.
• Add comments wherever applicable and especially around Apple API.
• Post-test sleep for dispatch queue for memory cleanup.
• Bug fixes.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 46.15385% with 14 lines in your changes missing coverage. Please review.

Project coverage is 79.59%. Comparing base (fdb053b) to head (eef0d7c).
Report is 169 commits behind head on grand_dispatch_queue.

Files with missing lines	Patch %	Lines
source/event_loop.c	57.14%	9 Missing ⚠️
source/linux/epoll_event_loop.c	0.00%	5 Missing ⚠️

Additional details and impacted files

@@                   Coverage Diff                    @@
##           grand_dispatch_queue     #704      +/-   ##
========================================================
- Coverage                 79.69%   79.59%   -0.11%     
========================================================
  Files                        30       30              
  Lines                      6117     6126       +9     
========================================================
+ Hits                       4875     4876       +1     
- Misses                     1242     1250       +8     

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[xiazhvera]

This should not be necessary as we already called dispatch_suspend(dispatch_loop->dispatch_queue); above.

[xiazhvera]

We probably wanna clarify that the destroy function will only release the memory of the entry. The caller should make sure to remove the priority_queue_node from its queue.