Rework WakePotential and Resonator

Add transverse wake potential to WakePotential and move class to dedicated file
Merge Resonator and TransverseResonator into Resonator with dedicated file
wakefunction_from_imp -> change trimming to allow for a float value
wakefunction_from_imp -> transverse impedance divided by 1j, to be checked with impedance convention but ok with benchmark
Wakefield -> add wake_components