fix: improve equatable comparison of QueryConstraint

[cbaker6]

New Pull Request Checklist

• I am not disclosing a vulnerability.
• I am creating this PR in reference to an issue.

Issue Description

The current QueryConstraint comparison attempts to cast Encodable constraints to NSObject's to check if they are equal. This can produce unintended results.

Related issue: #n/a

Approach

Compare encoded strings instead to produce a more reliable comparison of QueryConstraint's.

TODOs before merging

• Refactor files for code organization improvements
• Add entry to changelog
• Add changes to documentation (guides, repository pages, in-code descriptions)

[parse-github-assistant]

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[codecov]

Codecov Report

Merging #275 (6296bec) into main (af447a6) will increase coverage by 0.00%.
The diff coverage is 92.10%.

@@           Coverage Diff           @@
##             main     #275   +/-   ##
=======================================
  Coverage   82.23%   82.23%           
=======================================
  Files         103      104    +1     
  Lines       10577    10574    -3     
=======================================
- Hits         8698     8696    -2     
+ Misses       1879     1878    -1     

Impacted Files	Coverage Δ
Sources/ParseSwift/Extensions/Data.swift	100.00% <ø> (ø)
Sources/ParseSwift/Extensions/URLCache.swift	46.66% <ø> (ø)
...eSwift/InternalObjects/BaseParseInstallation.swift	36.36% <ø> (ø)
Sources/ParseSwift/Objects/ParseSession.swift	77.77% <ø> (+7.77%)	⬆️
...ources/ParseSwift/Types/ParseOperation+async.swift	100.00% <ø> (ø)
...rces/ParseSwift/Types/ParseOperation+combine.swift	100.00% <ø> (ø)
Sources/ParseSwift/Types/ParseRelation.swift	80.35% <ø> (ø)
Sources/ParseSwift/Types/Query.swift	93.60% <50.00%> (-0.02%)	⬇️
Sources/ParseSwift/Extensions/Encodable.swift	77.77% <77.77%> (ø)
Sources/ParseSwift/Coding/ParseCoding.swift	88.00% <100.00%> (+3.78%)	⬆️
... and 3 more

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