Add support for requesting disjoint paths

[italovalcy]

As discussed in PR kytos-ng/kytos#239 it would be interesting if pathfinder provides ways to request a maximum disjoint path from the user requests.

Blueprint EP029 has some information about the requirements for such feature.

Additionally, pathfinder can leverage some caching mechanism to avoid additional overhead when multiple requests are received for the same source/destination nodes. (unless some load balance is desirable)