API for Extended Euclidian Algorithm

[SK0M0R0H]

Currently, we use Extended Euclidian Algorithm only for inverse operation purposes (see inverse_extended_euclidean_algorithm).
The function returns only results for inverse operation and doesn't allow us to use it for any other purposes (e.g., GCD).
However, it costs us nothing to provide access to full Euclidian algorithm functionality in API, so I suppose we should do it.