Given a 2D integer array matrix, return the transpose of matrix.
The transpose of a matrix is the matrix flipped over its main diagonal, switching the matrix's row and column indices.
In other words, for every element at position matrix[i][j], its transposed position becomes result[j][i].
m == matrix.lengthn == matrix[i].length1 <= m, n <= 10001 <= m * n <= 10^5-10^9 <= matrix[i][j] <= 10^9matrix = [[1,2,3],[4,5,6],[7,8,9]][[1,4,7],[2,5,8],[3,6,9]]matrix = [[1,2,3],[4,5,6]][[1,4],[2,5],[3,6]]