Remove the phase tap changer FIXED_TAP regulation mode

[alicecaron]

Describe the current behavior

A PhaseTapChanger regulation mode can be set among the three following ones: FIXED_TAP, CURRENT_LIMITER, ACTIVE_POWER_CONTROL.

Describe the expected behavior

A PhaseTapChanger regulation mode can be set among the two following ones: CURRENT_LIMITER, ACTIVE_POWER_CONTROL, if not the validation level should remain EQUIPEMENT, an error message is logged and an exception is thrown if the boolean throwException is true.

To assure the retro compatibility on previous IIDM versions, when a phase tap changer is imported with a FIXED_TAP regulation mode, a warning message is logged and a teh regulation mode by default is be set (and should be CURRENT_LIMITER).

Describe the motivation

A regulation mode in FIXED_TAP usages are similar to the a non regulating PhaseTapChanger. This information is already represented with the regulating boolean. This mode induces confusion in the possible combinations of the (regulationMode, regulating) attributes couples.

Extra Information

PhaseShifterSetAsFixedTap and PhaseShifterShiftTap modifications will only set the PhaseTapChanger regulating value to false and set the tap position as given.

Impacts open load flow which needs to remove also the usages of FIXED_TAP regulation mode for a phase tap changer.