Converts a vector shaped like layer parameters to a 2D matrix.
In particular, we reshape the weights/filter component of the vector to be 2D, flattening all leading (input) dimensions. If there is a bias component, we concatenate it to the reshaped weights/filter component.
vector: A Tensor or pair of Tensors shaped like layer parameters.
A 2D Tensor with the same coefficients and the same output dimension.