query_int operator for PostgreSQL intarray type

### Is your proposal related to a problem?

I suggest adding support PostgreSQL intarray type and query_int operator.

### Describe the solution you'd like

I could be _query_int oparator, similar to _in for arrays

### Describe alternatives you've considered

I didn't find any alternatives.

No files or tests are named. Start by locating the existing PostgreSQL array filtering and _in operator handling, then review PostgreSQL's intarray type and query_int semantics. Done means the intended operator behavior is defined and supported with coverage for representative intarray queries.

Written by the indexing model from the issue text.