### 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
in.mappingParserContext,
            in.sourceToParse,
            in.ignoredFields,
            in.dynamicMappers,
            in.newFieldsSeen,
            in.dynamicObjectMappers,
            in.dynamicRuntimeFields,
            in.id,
            in.version,
            in.seqID,
            in.dimensions,
            parent,
            dynamic
        );
    }
    protected DocumentParserContext(
        MappingLookup mappingLookup,
        MappingParserContext mappingParserContext,
        SourceToParse source,
        ObjectMapper parent,
        ObjectMapper.Dynamic dynamic
    ) {
        this(
            mappingLookup,
            mappingParserContext,
            source,
            new HashSet<>(),
            new ArrayList<>(),
            new HashSet<>(),
            new HashMap<>(),