Add support for U gate

[khalatepradnya]

Required prerequisites

• [X] Search the issue tracker to check if your feature has already been mentioned or rejected in other issues.

Describe the feature

CUDA-Q should support the universal three-parameters operator (U or U3 gate)

The three parameters are Euler angles: θ, φ, and λ.

Matrix representation:

    U3(θ,φ,λ) = | cos(θ/2)            -exp(iλ) * sin(θ/2)       |
                | exp(iφ) * sin(θ/2)   exp(i(λ + φ)) * cos(θ/2) |

• [x] Define user API for C++ and Python
• [x] Enable usage in simulation
• [ ] Provide decomposition for hardware support