* [hlsl-out] fix matCx2 as global uniform
* [hlsl-out] update comments
* [hlsl-out] fix `row_major` not being written on global arrays of matrices and also write it on nested arrays of matrices
* [hlsl-out] fix matCx2's nested inside global arrays
* [hlsl-out] fix struct members of type array<matCx2>
* [hlsl-out] test mat2x4 to make sure our matCx2 code behaves properly