Define h coefficient from h_evaluator script

[jhdark]

WCLL_modelling/parameters_3D.py

Lines 197 to 202 in acbf735

	convective_flux_bz = F.ConvectiveFlux(
	h_coeff=5.025e03, T_ext=584.65, surfaces=ids_pipe_coolant_interface
	)
	convective_flux_fw = F.ConvectiveFlux(
	h_coeff=8.876e03 * 5, T_ext=584.65, surfaces=id_fw_coolant_interface
	)

Given there is now a script to evaluate the heat transfer coefficient, instead of using values, the evaluator should be imported and used in the file to evaluate the coefficient instead