GAPI (fluid): Sobel 3x3 optimization: CV_SIMD dynamic dispatching (#13133)

* GAPI (fluid): Sobel 3x3: remove template for run_sobel_row()

* GAPI (fluid): Sobel 3x3: dynamic dispatching of CV_SIMD code

* GAPI (fluid): Sobel 3x3 optimization: fixed CV_SIMD dynamic dispatcher