### Description

Dynamic mappings can greatly help the getting started experience but they currently don't apply to all types, one example is `dense_vector`.

It's been suggested to automatically map float arrays as dense vectors when there are more than 100 values, or a heuristic along these lines.
server/src/main/java/org/elasticsearch/index/mapper/DocumentParserContext.java
Set<String> ignoreFields,
        List<Mapper> dynamicMappers,
        Set<String> newFieldsSeen,
        Map<String, ObjectMapper> dynamicObjectMappers,
        List<RuntimeField> dynamicRuntimeFields,
        String id,
        Field version,
        SeqNoFieldMapper.SequenceIDFields seqID,
        DocumentDimensions dimensions,
        ObjectMapper parent,
        ObjectMapper.Dynamic dynamic
    ) {
        this.mappingLookup = mappingLookup;
        this.mappingParserContext = mappingParserContext;
        this.sourceToParse = sourceToParse;
        this.ignoredFields = ignoreFields;
        this.dynamicMappers = dynamicMappers;
        this.newFieldsSeen = newFieldsSeen;
        this.dynamicObjectMappers = dynamicObjectMappers;
        this.dynamicRuntimeFields = dynamicRuntimeFields;
        this.id = id;
        this.version = version;
        this.seqID = seqID;
        this.dimensions = dimensions;
        this.parent = parent;
        this.dynamic = dynamic;
    }
    private DocumentParserContext(ObjectMapper parent, ObjectMapper.Dynamic dynamic, DocumentParserContext in) {
        this(
            in.mappingLookup,