Problem: Rotate Image

Given an $n \times n$ matrix, rotate the matrix 90 degrees clockwise. The performed rotation should be in place, i.e., the given matrix is modified directly without allocating another matrix.

Note: The function should only return the modified input matrix.

Constraints:

• matrix.length $=$ matrix[i].length
• $1 \leq$ matrix.length $\leq 20$
• $-10^3 \leq$ matrix[i][j] $\leq 10^3$