[SEDONA-752] fix: NullPointerException from deep traversal beyond GeoJSON geometry level

[prantogg]

Did you read the Contributor Guide?

• Yes, I have read the Contributor Rules and Contributor Development Guide

Is this PR related to a ticket?

• Yes, and the PR name follows the format [SEDONA-XXX] my subject.
• Yes, and the PR name follows the format [GH-XXX] my subject. Closes #<issue_number>

What changes were proposed in this PR?

The GeoJSON reader's convertGeoJsonToGeometry and updateGeometrySchema methods were recursing into all nested StructType fields unconditionally. When a GeoJSON feature had nested struct properties (e.g., properties.prop1.nested_field), the traversal would descend into those property-level structs looking for a "geometry" field to convert. If any such struct happened to have fields that didn't match expected geometry patterns, this caused a NullPointerException.

This PR fixes the issue by:

• Adding a hasGeometryField helper that detects whether the current struct level contains a "geometry" field
• Once a geometry-level struct is found, only the "geometry" field is converted; sibling struct/array fields are passed through as-is without further recursion
• Adding null-safety checks throughout the traversal to prevent NPE on null fields
• Updating updateGeometrySchema with the same bounded-recursion logic so schema updates stop at the first geometry level

How was this patch tested?

• Updated the geojson_feature-collection.json test fixture to include nested struct properties (with multiple levels of nesting) that previously triggered the NPE
• Added a unit test updateGeometrySchema should update first geometry struct only that verifies schema traversal stops at the first geometry level and does not modify deeper "geometry" fields in property structs
• Existing GeoJSON read/write tests continue to pass

Did this PR include necessary documentation updates?

• No, this PR does not affect any public API so no need to change the documentation.