### 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
            IndexFieldData.Builder fielddataBuilder(DenseVectorFieldType denseVectorFieldType, FieldDataContext fieldDataContext) {
                return new VectorIndexFieldData.Builder(
                    denseVectorFieldType.name(),
                    CoreValuesSourceType.KEYWORD,
                    denseVectorFieldType.indexVersionCreated,
                    this,
                    denseVectorFieldType.dims,
                    denseVectorFieldType.indexed
                );
            }
            @Override
            public void checkVectorBounds(float[] vector) {
                checkNanAndInfinite(vector);
                StringBuilder errorBuilder = null;
                for (int index = 0; index < vector.length; ++index) {
                    float value = vector[index];
                    if (value % 1.0f != 0.0f) {
                        errorBuilder = new StringBuilder(
                            "element_type ["
                                + this
                                + "] vectors only support non-decimal values but found decimal value ["
                                + value
                                + "] at dim ["
                                + index
                                + "];"
                        );
                        break;
                    }
                    if (value < Byte.MIN_VALUE || value > Byte.MAX_VALUE) {