fix(DataStore): Nested query predicates are not stored properly

[wooj2]

For Reference, android code:
https://github.com/aws-amplify/amplify-android/blame/12ec8e9819228f63bd677a0431a5ab191f79d9e1/core/src/main/java/com/amplifyframework/core/model/query/predicate/QueryPredicateGroup.java#L77

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

Merging #905 (f921257) into main (e2fe056) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #905      +/-   ##
==========================================
- Coverage   64.89%   64.89%   -0.01%     
==========================================
  Files         862      862              
  Lines       34182    34178       -4     
==========================================
- Hits        22182    22179       -3     
+ Misses      12000    11999       -1     

Flag	Coverage Δ
API_plugin_unit_test	62.49% <ø> (-0.08%)	⬇️
Analytics_plugin_unit_test	72.38% <ø> (ø)
Auth_plugin_unit_test	15.79% <ø> (ø)
DataStore_plugin_unit_test	83.03% <ø> (ø)
Predictions_plugin_unit_test	42.11% <ø> (ø)
Storage_plugin_unit_test	74.74% <ø> (ø)
build_test_amplify	64.29% <0.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...fy/Categories/DataStore/Query/QueryPredicate.swift	0.00% <0.00%> (ø)
...n/Operation/AWSGraphQLOperation+APIOperation.swift	50.84% <0.00%> (-6.78%)	⬇️
.../DataStore/Model/Internal/Schema/ModelSchema.swift	85.29% <0.00%> (-2.95%)	⬇️
...in/Operation/AWSGraphQLSubscriptionOperation.swift	70.08% <0.00%> (+1.70%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e2fe056...f921257. Read the comment docs.

[drochetti]

makes more sense now! thanks for catching that

[wooj2]

makes more sense now! thanks for catching that

Shout out to @richardmcclellan for helping me debug this!