feat(ParseQuery): support using aggregate on top of constructed query

[RaschidJFR]

Closes #1171

Enable using a constructed query with aggregate, passing the where key to the aggregate pipeline as match.

Example:

await new Parse.Query(TestObject)
  .equalTo('name', 'foo')
  .aggregate(pipeline);  // This now aggregates only objects with name 'foo'

See #1171 for further details.

[codecov]

Codecov Report

Merging #1170 into master will decrease coverage by 0.03%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master    #1170      +/-   ##
==========================================
- Coverage   92.38%   92.34%   -0.04%     
==========================================
  Files          54       54              
  Lines        5290     5293       +3     
  Branches     1189     1191       +2     
==========================================
+ Hits         4887     4888       +1     
- Misses        403      405       +2     

Impacted Files	Coverage Δ
src/ParseQuery.js	96.00% <33.33%> (-0.28%)	⬇️

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