fix: throw .missingObjectId error when fetching

[cbaker6]

New Pull Request Checklist

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

Issue Description

The SDK currently throws an .unknown error specifying the objectId is missing (when it's actually missing), but it can actually throw .missingObjectId from within the SDK.

Related issue: #n/a

Approach

Throw .missingObjectId in the above situation.

TODOs before merging

• Add tests
• Nit some of the docs
• Add changes to documentation (guides, repository pages, in-code descriptions)

[parse-github-assistant]

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[codecov]

Codecov Report

Merging #300 (23c0dba) into main (ebaaf12) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #300      +/-   ##
==========================================
- Coverage   83.66%   83.64%   -0.03%     
==========================================
  Files         105      105              
  Lines       11187    11190       +3     
==========================================
  Hits         9360     9360              
- Misses       1827     1830       +3     

Impacted Files	Coverage Δ
...ParseSwift/Objects/ParseInstallation+combine.swift	92.94% <ø> (ø)
Sources/ParseSwift/API/API+Command.swift	83.77% <100.00%> (+0.47%)	⬆️
Sources/ParseSwift/Objects/ParseInstallation.swift	80.66% <100.00%> (+0.02%)	⬆️
Sources/ParseSwift/Objects/ParseUser.swift	80.73% <100.00%> (+0.01%)	⬆️
Sources/ParseSwift/LiveQuery/ParseLiveQuery.swift	72.92% <0.00%> (-0.74%)	⬇️

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