feat: add explain MongoDB queries

[cbaker6]

New Pull Request Checklist

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

Issue Description

The Swift SDK can't explain MongoDB queries due to a bug on the server-side response. PR parse-community/parse-server#7440 was created on the server, but the server team has chosen not to fix the code.

Originally discussed in: https://community.parseplatform.org/t/explain-result-in-parseswift/1557

Related issue: #N/A parse-community/parse-server#7442

Approach

Add a new internal response type that doesn't expect results to be an array. When the user wants to explain a mongo query, they set the flag, isUsingMongoDB=true. This allows the mongo explained queries to use the same methods as the ones already in the SDK.

TODOs before merging

• Add tests
• 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 #314 (cd8b006) into main (e6c2db2) will increase coverage by 0.00%.
The diff coverage is 94.05%.

@@           Coverage Diff            @@
##             main     #314    +/-   ##
========================================
  Coverage   84.62%   84.62%            
========================================
  Files         114      114            
  Lines       11718    11845   +127     
========================================
+ Hits         9916    10024   +108     
- Misses       1802     1821    +19     

Impacted Files	Coverage Δ
Sources/ParseSwift/API/Responses.swift	91.25% <ø> (ø)
Sources/ParseSwift/Types/Query.swift	92.28% <92.81%> (-0.89%)	⬇️
Sources/ParseSwift/Types/Query+async.swift	100.00% <100.00%> (ø)
Sources/ParseSwift/Types/Query+combine.swift	100.00% <100.00%> (ø)
Sources/ParseSwift/LiveQuery/ParseLiveQuery.swift	72.92% <0.00%> (-0.60%)	⬇️

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