Map fermionic hamiltonian to bosonic hamiltonian in Fock basis

[Hugh-888]

Add class FermionMapBoson for mapping the fermionic Hamiltonian to the bosonic Hamiltonian in Fock basis.
Example:

h_z = 3
geometry = [("H", (0, 0, 0)), ("H", (0, 0, h_z))]
basis = "sto-3g"
multiplicity = 1
charge = 0
occupied_indices = []
active_indices = [0,1]
config = {'geometry': geometry, 'basis':basis, 'multiplicity':multiplicity, 'charge':charge, 'n_ele':2, 'n_orbit':4,
          'occupied_indices':occupied_indices, 'active_indices': active_indices}

fermion_map = dqp.ansatz.FermionMapBoson(config)
h_f = fermion_map.construct_h_fermion()
energy2 = np.linalg.eigvals(h_f)
constant = fermion_map.constant
print(fermion_map.fci_energy(),  np.min(energy2) + constant)

h_fock = fermion_map.mapping()
h_fock