Find a path from the top-left to the bottom-right of a matrix using BFS.
The matrix contains 0 for an open cell and 1 for a blocked cell. Move only up, down, left, or right, and return the path as a list of [row, column] coordinates. Return an empty list if no path exists. If multiple shortest paths exist, any one is valid.
Function: def find_path(matrix):
Input/Output: matrix is a non-empty rectangular binary matrix; return a coordinate list including the start and destination, or [].
def find_path(matrix):