[NFC] Unify QGTJacoboian implementations
Created by: PhilipVinc
This changes nothing for the user.
Internally, it changes the way we store the jacobian of non holomorphic wavefuntions in QGTJacobianPyTree to store it as a (N_samples, 2, ...)
instead of (2*Nsamples, ...)
. Performance wise this changes nothing, but it makes the implementation cleaner and allows to finally unify those two implementations
This also fixes a bug where holomorphic=False
for ExactState
returned the imaginary part of the QGT...