Don't query server when limit is zero

[cbaker6]

When a query has a limit of zero, there's no need to send the information to the server.

• Add check for limit zero
• Fixed a bug in countExplain query where the return type wan't an array
• Add test cases

[codecov]

Codecov Report

Merging #189 (bd188c1) into main (fca7ab1) will increase coverage by 0.20%.
The diff coverage is 100.00%.

❗ Current head bd188c1 differs from pull request most recent head e7cb9b1. Consider uploading reports for the commit e7cb9b1 to get more accurate results

@@            Coverage Diff             @@
##             main     #189      +/-   ##
==========================================
+ Coverage   82.47%   82.67%   +0.20%     
==========================================
  Files          71       71              
  Lines        6755     6823      +68     
==========================================
+ Hits         5571     5641      +70     
+ Misses       1184     1182       -2     

Impacted Files	Coverage Δ
Sources/ParseSwift/Types/Query+combine.swift	100.00% <100.00%> (ø)
Sources/ParseSwift/Types/Query.swift	94.43% <100.00%> (+1.03%)	⬆️

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