Save lift tests to InferenceData

[wd60622]

This would be required to rebuild same model after using lift test methods.

Currently missing:

• save the lift tests to the fit_data group
• upon load, add the lift tests to the model likelihood
  • Would be done here

An alternative to this would be to save the lift test to a separate group. However, this would likely cause some additional complexity and would have to capture additional warnings. The fit_data just runs the risk of having to change the structure of the fit_data group itself and likely have to have a version bump of the model.

[wd60622]

The kwargs used with the would have to be saved off as well or the reconstructed model would not be the same

pymc-marketing/pymc_marketing/mmm/delayed_saturated_mmm.py

Lines 1735 to 1740 in 4bddf94

	def add_lift_test_measurements(
	self,
	df_lift_test: pd.DataFrame,
	dist: type[pm.Distribution] = pm.Gamma,
	name: str = "lift_measurements",
	) -> None:

Potentially these kwargs in the attrs like in the save and load methods. This seems to require that each df_lift_test would have to be saved in separate variable? Maybe using another group like lift_tests would be more clear?