fix: use select for ParseLiveQuery when fields are not present

[cbaker6]

New Pull Request Checklist

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

Issue Description

When using ParseLiveQuery, developers current have to call the fields method on query even though they may have already called select. This requires the developer to have to take an additional step when using Live Query.

Related issue: #n/a

Approach

When using the Query for ParseLiveQuery, setting fields will take precedence over select. If fields are not set, the select keys will be used.

TODOs before merging

• Add tests
• Add entry to changelog
• Add changes to documentation (guides, repository pages, in-code descriptions)

[parse-github-assistant]

Thanks for opening this pull request!

• 🎉 We are excited about your hands-on contribution!

[codecov]

Codecov Report

Merging #377 (c572d31) into main (4ccb8a6) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #377      +/-   ##
==========================================
+ Coverage   89.50%   89.54%   +0.03%     
==========================================
  Files         152      152              
  Lines       13965    13969       +4     
==========================================
+ Hits        12499    12508       +9     
+ Misses       1466     1461       -5     

Impacted Files	Coverage Δ
Sources/ParseSwift/Types/Query.swift	95.14% <ø> (ø)
Sources/ParseSwift/LiveQuery/Messages.swift	100.00% <100.00%> (ø)
Sources/ParseSwift/LiveQuery/ParseLiveQuery.swift	76.16% <100.00%> (+0.06%)	⬆️
Sources/ParseSwift/Objects/ParseObject.swift	84.95% <0.00%> (-0.16%)	⬇️
Sources/ParseSwift/Objects/ParseUser.swift	86.29% <0.00%> (+0.17%)	⬆️
Sources/ParseSwift/Coding/ParseEncoder.swift	78.23% <0.00%> (+0.45%)	⬆️

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