Sizing calculator for vector search

There are multiple options to index vectors. Each of these options results in different needs for computing resources. Currently we provide all the information [here](https://www.elastic.co/docs/deploy-manage/production-guidance/optimize-performance/approximate-knn-search#_ensure_data_nodes_have_enough_memory). We want to add a calculator so users can enter their index type, quantization, number of vectors and dimensionality, and get the required off-heap RAM and disk.