Feature: implement explicit index queries on arrays in Postgres stores

[wolf4ood]

Feature Request

Support explicit indexes when querying arrays in Postgres stores.
The current behavior throws an exception on failed do find the mapping.

For now the collectionIndexQuery flags in all base tests is disabled in all PG tests

Which Areas Would Be Affected?

All Postgres stores.

Why Is the Feature Desired?

To achieve feature parity with InMemory and ComosDB stores.

Solution Proposal

The query in case of an exact index on a collection should be rewritten using the -> operator with works on the collection field
by providing in the right operand the index of the element we are interested in.

Type of Issue

i.e., new feature, improvement, cleanup, etc.

Checklist

• assigned appropriate label?
• Do NOT select a milestone or an assignee!

[github-actions]

This issue is stale because it has been open for 14 days with no activity.

[github-actions]

This issue is stale because it has been open for 28 days with no activity.

[ndr-brt]

This was already solved by #3330