Fix/3678 overloaded query constraints

[flovilmart]

Fixes #3678

Having 2 constraints on the same key when a pointer is set will yield an odd where constraint:

author: {
  __type: Pointer,
  objectId: "Author",
  $nin: [...]
}

this PR transforms the constraint to:

author: {
  $eq: {
    __type: Pointer,
   objectId: "Author",
  }
  $nin: [...]
}

In order to be correctly processed.

We should also probably investigate why this happens in the 1st place, the JS SDK handles this in a very odd way.

[codecov]

Codecov Report

Merging #3723 into master will decrease coverage by 0.01%.
The diff coverage is 95.45%.

@@            Coverage Diff             @@
##           master    #3723      +/-   ##
==========================================
- Coverage   90.22%   90.21%   -0.02%     
==========================================
  Files         114      114              
  Lines        7461     7491      +30     
==========================================
+ Hits         6732     6758      +26     
- Misses        729      733       +4

Impacted Files	Coverage Δ
src/RestQuery.js	94.91% <95.45%> (+0.03%)	⬆️
src/Adapters/Auth/meetup.js	84.21% <0%> (-5.27%)	⬇️
...dapters/Storage/Postgres/PostgresStorageAdapter.js	95.17% <0%> (-0.28%)	⬇️
src/RestWrite.js	94.3% <0%> (ø)	⬆️
src/Controllers/SchemaController.js	97.05% <0%> (+0.05%)	⬆️

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[acinader]

!==