Bring back st_d_within for geographic lookups

### Component
c/v3-engine
c/v3-ndc-postgres

### Is your proposal related to a problem?
In Hasura v2, geographic lookups were easily performed using st_d_within, allowing users to find relevant objects around a given location by providing a point and search radius.

In Hasura v3, only st_within is supported. As a result, performing similar lookups now requires generating the lookup geometry on the client side beforehand.

### Describe the solution you'd like
Reimplement st_d_within.

### Describe alternatives you've considered
Generating lookup geometries on the client side.

Start in c/v3-engine and c/v3-ndc-postgres by tracing the existing st_within support. Compare the described Hasura v2 st_d_within behavior with the v3 geographic lookup path and determine the required interface and validation. Done means users can perform distance-based geographic lookups with st_d_within without generating lookup geometries client-side.

Written by the indexing model from the issue text.