Implement optimization method for unitary matrix

[MKrbm]

Implement unitary matrix and optimize unitary matrix with Riemannian Gradient.

Optimization

• Allow to receive dtype = torch.complex128 / 64
• Implement Riemannian Gradient for unitary matrix.
• Implement unittest for Riemannian Gradient optimization.

Check If unitary is better than orthogonal

• Optimize unitary matrix for random FF
• Check weather unitary is better than orthogonal or not.