### 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
for (int index = 0; index < vector.length; ++index) {
                float value = vector[index];
                if (Float.isNaN(value)) {
                    errorBuilder = new StringBuilder(
                        "element_type [" + this + "] vectors do not support NaN values but found [" + value + "] at dim [" + index + "];"
                    );
                    break;
                }
                if (Float.isInfinite(value)) {
                    errorBuilder = new StringBuilder(
                        "element_type ["
                            + this
                            + "] vectors do not support infinite values but found ["
                            + value
                            + "] at dim ["
                            + index
                            + "];"
                    );
                    break;
                }
            }
            if (errorBuilder != null) {
                throw new IllegalArgumentException(appendErrorElements(errorBuilder, vector).toString());
            }
        }
        StringBuilder appendErrorElements(StringBuilder errorBuilder, float[] vector) {
            
            errorBuilder.append(" Preview of invalid vector: [");
            for (int i = 0; i < Math.min(5, vector.length); i++) {
                if (i > 0) {