### 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
public void testNumSides() {
        double radiusDistanceMeters = randomDoubleBetween(0.01, 6371000, true);
        CircleShapeFieldType shapeType = randomFrom(SHAPE, GEO_SHAPE);
        CircleProcessor processor = new CircleProcessor("tag", null, "field", "field", false, radiusDistanceMeters, shapeType);
        
        assertThat(processor.numSides(radiusDistanceMeters), equalTo(4));
        
        assertThat(processor.numSides(0), equalTo(4));
        
        assertThat(processor.numSides(Math.pow(radiusDistanceMeters, 100)), equalTo(1000));
        
        assertThat(processor.numSides(5 * radiusDistanceMeters), equalTo(10));
    }
    public void testFieldNotFound() throws Exception {
        CircleProcessor processor = new CircleProcessor("tag", null, "field", "field", false, 10, GEO_SHAPE);
        IngestDocument ingestDocument = RandomDocumentPicks.randomIngestDocument(random(), new HashMap<>());
        Exception e = expectThrows(Exception.class, () -> processor.execute(ingestDocument));
        assertThat(e.getMessage(), containsString("not present as part of path [field]"));
    }
    public void testFieldNotFoundWithIgnoreMissing() throws Exception {
        CircleProcessor processor = new CircleProcessor("tag", null, "field", "field", true, 10, GEO_SHAPE);
        IngestDocument originalIngestDocument = RandomDocumentPicks.randomIngestDocument(random(), new HashMap<>());
        IngestDocument ingestDocument = new IngestDocument(originalIngestDocument);