### 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/main/java/org/elasticsearch/xpack/spatial/ingest/CircleProcessor.java
private final boolean ignoreMissing;
    private final double errorDistance;
    private final CircleShapeFieldType circleShapeFieldType;
    CircleProcessor(
        String tag,
        String description,
        String field,
        String targetField,
        boolean ignoreMissing,
        double errorDistance,
        CircleShapeFieldType circleShapeFieldType
    ) {
        super(tag, description);
        this.field = field;
        this.targetField = targetField;
        this.ignoreMissing = ignoreMissing;
        this.errorDistance = errorDistance;
        this.circleShapeFieldType = circleShapeFieldType;
    }
    @Override
    @SuppressWarnings("unchecked")
    public IngestDocument execute(IngestDocument ingestDocument) {
        Object obj = ingestDocument.getFieldValue(field, Object.class, ignoreMissing);
        if (obj == null && ignoreMissing) {
            return ingestDocument;
        } else if (obj == null) {
            throw new IllegalArgumentException("field [" + field + "] is null, cannot process it.");
        }
        final Map<String, Object> valueWrapper;
        if (obj instanceof Map || obj instanceof String) {