Improve aggregate by accepting any Encodable type

[cbaker6]

The are some updates to aggregate. Aggregate technically can't be used yet in ParseSwift because it uses POST instead of

• Remove MasterKey check for File and let server decide to delete file
• Make distinct use aggregate
• To use explain, findExplain, firstExplain, countExplain, etc.
• Add changelog
• Add documentation
• Prepare for release

[codecov]

Codecov Report

Merging #122 (31a4097) into main (ee481d4) will increase coverage by 0.41%.
The diff coverage is 96.47%.

❗ Current head 31a4097 differs from pull request most recent head c6b98a0. Consider uploading reports for the commit c6b98a0 to get more accurate results

@@            Coverage Diff             @@
##             main     #122      +/-   ##
==========================================
+ Coverage   80.87%   81.28%   +0.41%     
==========================================
  Files          65       65              
  Lines        5589     5701     +112     
==========================================
+ Hits         4520     4634     +114     
+ Misses       1069     1067       -2     

Impacted Files	Coverage Δ
Sources/ParseSwift/Types/ParseFile+combine.swift	100.00% <ø> (ø)
Sources/ParseSwift/Types/Query.swift	91.45% <95.83%> (+0.77%)	⬆️
Sources/ParseSwift/Types/ParseFile.swift	87.81% <100.00%> (-0.42%)	⬇️
Sources/ParseSwift/Types/Query+combine.swift	100.00% <100.00%> (ø)
Sources/ParseSwift/Objects/ParseObject.swift	77.00% <0.00%> (-0.27%)	⬇️
Sources/ParseSwift/Objects/ParseUser.swift	81.67% <0.00%> (+0.15%)	⬆️
Sources/ParseSwift/Coding/AnyEncodable.swift	34.75% <0.00%> (+4.25%)	⬆️
Sources/ParseSwift/Protocols/Deletable.swift	100.00% <0.00%> (+100.00%)	⬆️

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