fix: Only encode email on ParseUser if different from Keychain

[cbaker6]

New Pull Request Checklist

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

Issue Description

Builds onto #241 to ensure to only encode email if different from Keychain on Apple devices.

Related issue: #239

Approach

Compare email against Keychain email on Apple devices.

TODOs before merging

• Add tests
• Add entry to changelog
• Documentation nits
• Prepare for release

[codecov]

Codecov Report

Merging #256 (db63447) into main (1385abf) will increase coverage by 0.03%.
The diff coverage is 93.33%.

@@            Coverage Diff             @@
##             main     #256      +/-   ##
==========================================
+ Coverage   76.75%   76.79%   +0.03%     
==========================================
  Files          98       98              
  Lines       10403    10412       +9     
==========================================
+ Hits         7985     7996      +11     
+ Misses       2418     2416       -2     

Impacted Files	Coverage Δ
Sources/ParseSwift/Objects/ParseInstallation.swift	77.36% <0.00%> (ø)
Sources/ParseSwift/Parse.swift	98.72% <ø> (ø)
Sources/ParseSwift/Objects/ParseUser.swift	79.85% <100.00%> (+0.19%)	⬆️
Sources/ParseSwift/LiveQuery/ParseLiveQuery.swift	72.94% <0.00%> (-0.15%)	⬇️
Sources/ParseSwift/Coding/ParseEncoder.swift	73.60% <0.00%> (+0.35%)	⬆️

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