AA006: Convert Coordinates in RoutePlanner to use std::pair

[Heckart]

Assigned Dev: N/A

Description: Halfway through making the RoutePlanner class, I switched from using int row and int column to using a std::pair<int, int> to represent coordinates. Converting all coordinate pairs to std::pair instead of separate ints will allow us to consolidate some functions into one and massively clean up the code in many other functions.
Priority: Low
User Story: As a user, I don't know how this is relevant. Maybe I want the programmers to be able to more easily read their code.
Acceptance Criteria: In the RoutePlanner, whenever a coordinate pair is used as two separate integers, it is changed to a std::pair<int, int> similar to how it is done in isTurnValid(). Rerun unit tests to ensure you didn't break anything.