Normalize and scale load profile, refactor (mostly heating) load code

[Bill-Becker]

• Add new input for each load called normalize_and_scale_load_profile_input which takes the input custom load profile (e.g. ElectricLoad.loads_kw), normalizes it to timestep_energy/yearly_energy for each timestep, and then applies and scales that normalized profile to the input annual monthly energy values.
  • Before, we could only scale annual or monthly energy inputs to the CRB profiles.
  • This leverages the CRB calculations for applying and scaling annual and monthly energy to the load profile.
  • This will be especially helpful to use along with the upcoming Load Profile Builder feature in the web tool
• Put all of the default annual_[energy] data for CRBs by city/zone into .json files in the data/load_profiles folder, and then load that data within the load profile constructor functions (BuiltIn[Load]) where they lived before (hard to navigate those load file with all that data).
• Consolidate all of the duplicate code for processing the inputs and building structs for the three different types of heating loads into a single HeatingLoad and BuiltInHeatingLoad functions (3x2=6 functions down to 2) with a new argument of (heating_)load_type.
• Update the simulated_load function for improved validation flow and adding the normalize_and_scale_load_profile_input option