Pv/qgt
Created by: PhilipVinc
This PR is based upon #1310 and includes its changes
This PR implements removes a lot of duplicated code from QGTJacobianDense
by changing our implementation of nkjax.tree_to_Real
to concatenate all real parts before all imaginary parts, so that its logic can be used by QGTJacobianDense.
Done in collaboration with @inailuig