### 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/vectors/DenseVectorFieldMapper.java
@Override
            double parseKnnVectorToByteBuffer(DocumentParserContext context, DenseVectorFieldMapper fieldMapper, ByteBuffer byteBuffer)
                throws IOException {
                double dotProduct = 0f;
                int index = 0;
                for (Token token = context.parser().nextToken(); token != Token.END_ARRAY; token = context.parser().nextToken()) {
                    fieldMapper.checkDimensionExceeded(index, context);
                    ensureExpectedToken(Token.VALUE_NUMBER, token, context.parser());
                    int value = context.parser().intValue(true);
                    if (value < Byte.MIN_VALUE || value > Byte.MAX_VALUE) {
                        throw new IllegalArgumentException(
                            "element_type ["
                                + this
                                + "] vectors only support integers between ["
                                + Byte.MIN_VALUE
                                + ", "
                                + Byte.MAX_VALUE
                                + "] but found ["
                                + value
                                + "] at dim ["
                                + index
                                + "];"
                        );
                    }
                    byteBuffer.put((byte) value);
                    dotProduct += value * value;
                    index++;
                }
                fieldMapper.checkDimensionMatches(index, context);
                return dotProduct;