Switched context header X-Parse-Context to X-Parse-Cloud-Context

[cbaker6]

Adjusted to new context header from server. Also improved ParseLiveQuery and some flaky testcases introduced in #172.

• Switched from X-Parse-Context to X-Parse-Cloud-Context. Depends on Accept context via header X-Parse-Cloud-Context parse-server#7437
• ParseError now conforms to CustomDebugStringConvertible
• Improved LiveQuery testcases
• Improved LiveQuery playgrounds
• Simplify release process, now only need to update Sources/ParseSwift/ParseConstants.swift and CHANGELOG.md. The docs and podspec will automatically pull from the tag.
• Added changelog entry
• Prepare for new release

[codecov]

Codecov Report

Merging #170 (c2d25fc) into main (2e9b772) will increase coverage by 0.62%.
The diff coverage is 82.35%.

@@            Coverage Diff             @@
##             main     #170      +/-   ##
==========================================
+ Coverage   81.55%   82.17%   +0.62%     
==========================================
  Files          71       71              
  Lines        6641     6643       +2     
==========================================
+ Hits         5416     5459      +43     
+ Misses       1225     1184      -41     

Impacted Files	Coverage Δ
Sources/ParseSwift/LiveQuery/ParseLiveQuery.swift	75.72% <76.00%> (-0.32%)	⬇️
Sources/ParseSwift/API/API.swift	98.26% <100.00%> (ø)
Sources/ParseSwift/Types/ParseError.swift	100.00% <100.00%> (ø)
Sources/ParseSwift/Coding/ParseEncoder.swift	74.83% <0.00%> (-0.33%)	⬇️
Sources/ParseSwift/Objects/ParseUser.swift	81.52% <0.00%> (-0.16%)	⬇️
Sources/ParseSwift/Types/Query.swift	93.38% <0.00%> (+0.17%)	⬆️
Sources/ParseSwift/Coding/AnyEncodable.swift	61.84% <0.00%> (+0.65%)	⬆️
Sources/ParseSwift/API/URLSession+extensions.swift	80.21% <0.00%> (+2.19%)	⬆️
Sources/ParseSwift/Storage/ParseFileManager.swift	90.07% <0.00%> (+7.63%)	⬆️
... and 2 more

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