Add support for query.explain and query.hint

[dplewis]

New Feature / Enhancement Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.

Feature / Enhancement Description

This feature already exists in the Javascript SDK. parse-community/Parse-SDK-JS#1054

parse-community/parse-server#6288

[parse-github-assistant]

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