Feature: Compute mutual overlaps of vectors or density matrices

[vprusso]

It would be helpful to have a function that provides the mutual overlaps (inner products) of a list of numpy arrays (representing vectors of quantum states).

Something like the following:

def compute_overlaps(vectors: list[np.ndarray]) -> list[np.ndarray]:
    """Returns list of all overlaps such that i != j."""
    inner_products = []
    for i in range(len(vectors)):
        for j in range(i + 1, len(vectors)):
            inner_products.append(np.vdot(vectors[i], vectors[j]))
    return inner_products

In addition, we can refactor is_mutually_orthogonal.py to use this function as there is going to be a good amount of redundancy between these functions as is.

The function should also include proper documentation, examples, and tests.