### Description

It would be really great if [CircleProcessor.java](https://github.com/elastic/elasticsearch/blob/0699c9351f1439e246d408fd6538deafde4087b6/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/ingest/CircleProcessor.java) could be published in some maven artifact.
We are thinking to convert Geoshape Circle into Geoshape Polygon on application side instead of ElasticSearch Server side. The benefits of it is that it would make possible for us to choose `error_distance` dynamically depending on different conditions.
With direct code access to [CircleProcessor.java](https://github.com/elastic/elasticsearch/blob/0699c9351f1439e246d408fd6538deafde4087b6/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/ingest/CircleProcessor.java) and [SpatialUtils.java](https://github.com/elastic/elasticsearch/blob/0699c9351f1439e246d408fd6538deafde4087b6/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/SpatialUtils.java) it would be possible to make application side custom conversion logic.
ElasticSearch version: >= 8
x-pack/plugin/spatial/src/test/java/org/elasticsearch/xpack/spatial/ingest/CircleProcessorTests.java
Map<String, Object> polyMap = ingestDocument.getFieldValue("field", Map.class);
        XContentBuilder builder = XContentFactory.jsonBuilder();
        GeoJson.toXContent(expectedPoly, builder, ToXContent.EMPTY_PARAMS);
        Tuple<XContentType, Map<String, Object>> expected = XContentHelper.convertToMap(
            BytesReference.bytes(builder),
            true,
            XContentType.JSON
        );
        assertThat(polyMap, equalTo(expected.v2()));
    }
    public void testWKT() {
        Circle circle = new Circle(101.0, 0.0, 2);
        HashMap<String, Object> map = new HashMap<>();
        map.put("field", WellKnownText.toWKT(circle));
        Geometry expectedPoly = SpatialUtils.createRegularGeoShapePolygon(circle, 4);
        IngestDocument ingestDocument = TestIngestDocument.withDefaultVersion(map);
        CircleProcessor processor = new CircleProcessor("tag", null, "field", "field", false, 2, GEO_SHAPE);
        processor.execute(ingestDocument);
        String polyString = ingestDocument.getFieldValue("field", String.class);
        assertThat(polyString, equalTo(WellKnownText.toWKT(expectedPoly)));
    }
    public void testInvalidWKT() {
        HashMap<String, Object> map = new HashMap<>();
        map.put("field", "invalid");
        IngestDocument ingestDocument = TestIngestDocument.withDefaultVersion(map);
        CircleProcessor processor = new CircleProcessor("tag", null, "field", "field", false, 10, GEO_SHAPE);
        IllegalArgumentException e = expectThrows(IllegalArgumentException.class, () -> processor.execute(ingestDocument));
        assertThat(e.getMessage(), equalTo("invalid circle definition"));
        map.put("field", "POINT (30 10)");
        e = expectThrows(IllegalArgumentException.class, () -> processor.execute(ingestDocument));