Improve threading

[cbaker6]

• Only use callbackQueue in the parse URLSession for progress updates (meaning progress can be specified on any queue the user wants.
• In ParseURLSessionDelegate auto cleanup delegate task dictionary
• Instead, each method in a ParseObject/Type is responsible for returning data to the correct thread
• Fixed some places in ParseObject delete where a delete error might not have been given back to the user
• Make saveAll run on it's own thread. When saveAll was fixed previously, depending on how it was called the async version could have ran on the main thread in which the OS would have started complaining eventually.

I'm hoping this fixes the random failure that only occurred in the 100 thread tests that has been hard to find...

[codecov]

Codecov Report

Merging #51 (005406f) into main (806e026) will decrease coverage by 0.45%.
The diff coverage is 67.41%.

@@            Coverage Diff             @@
##             main      #51      +/-   ##
==========================================
- Coverage   76.71%   76.25%   -0.46%     
==========================================
  Files          42       42              
  Lines        3757     3883     +126     
==========================================
+ Hits         2882     2961      +79     
- Misses        875      922      +47     

Impacted Files	Coverage Δ
...urces/ParseSwift/API/ParseURLSessionDelegate.swift	21.05% <7.14%> (-3.09%)	⬇️
Sources/ParseSwift/Objects/ParseObject.swift	75.36% <60.17%> (-2.13%)	⬇️
Sources/ParseSwift/Objects/ParseUser.swift	75.73% <61.25%> (-2.77%)	⬇️
Sources/ParseSwift/Objects/ParseInstallation.swift	81.60% <64.56%> (-1.48%)	⬇️
Sources/ParseSwift/API/API+Commands.swift	82.31% <88.88%> (+1.56%)	⬆️
Sources/ParseSwift/Types/ParseFile.swift	88.23% <92.00%> (+0.94%)	⬆️
Sources/ParseSwift/Types/Query.swift	91.80% <96.15%> (+0.25%)	⬆️
Sources/ParseSwift/API/URLSession+extensions.swift	78.57% <100.00%> (+0.52%)	⬆️
Sources/ParseSwift/LiveQuery/LiveQuerySocket.swift	61.40% <100.00%> (ø)
Sources/ParseSwift/Types/ParseCloud.swift	97.43% <100.00%> (+0.13%)	⬆️
... and 1 more

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