HNSW: Insertion and Graph Construction

Implement the probabilistic function to assign a random maximum layer for a new vector upon insertion.

Implement the main insertion algorithm, which finds neighbors for the new node from its top layer down to layer 0.

For each layer during insertion, use the `SEARCH-LAYER` algorithm to find candidate neighbors.

Implement the neighborhood selection heuristic to choose the best `M` neighbors for the new node from the candidates.

Implement the logic to create bidirectional connections between the new node and its selected neighbors.

Implement connection pruning to ensure nodes do not exceed their maximum connection limit (`M_max`) after an insertion.