`nidmm.Session.get_cal_date_and_time` and `get_last_cal_temp` is different from other nimi-python drivers

[marcoskirsch]

Description of issue

nidmm.Session.get_cal_date_and_time and get_last_cal_temp are inconsistent with the rest of nimi-python.
Instead of one method that takes in an enum, we should have two methods for each:

• get_ext_cal_last_date_and_time and get_self_cal_last_date_and_time.
• get_ext_cal_last_temp and get_self_cal_last_temp
  Note - this inconsistency was inherited from the C/LabVIEW API.