Allow configuration of Solr spatial_field name for spatial queries

[minhajuddin2510]

Problem

Currently, the Solr spatial field name is hardcoded as spatial_geom when building queries with the ckanext.spatial.solr_query config in ckanext-spatial. This makes it impossible to use a different field name in the Solr schema without directly modifying the extension code, restricting schema flexibility for deployments with custom Solr setups.

Proposal

• Introduce a configuration option (like ckanext.spatial.spatial_field_name) to allow users to specify the Solr spatial field name to use for spatial queries.
• The value should default to spatial_geom to preserve current behavior.
• Use this dynamic field name both when formatting the Solr query string and when indexing datasets (where applicable).

Example

ckanext.spatial.spatial_field_name = my_custom_geom_field

Query string example:

ckanext.spatial.solr_query = {{!field f={spatial_field}}}Intersects(ENVELOPE({minx}, {maxx}, {maxy}, {miny}))