Provide external driving signals to various py_sims

[misi9170]

FlorisStandin, PySAM, etc could be driven by external weather signals, for example:

• wind speed
• wind direction
• solar irradiance (multiple channels)
• temperature
• humidity

as well as grid signals, for example:

• load profile
• electricity price

These should be read in to the Hercules simulator as external_signals, similar to the way that the "wind_power_reference" is read in the WHOC example wind_farm_power_tracking_florisstandin here.

Ideally, each signals will have it's own time column, so that different signal resolutions may be passed. Also, each pysim will need to be updated to accept the external_signals

[genevievestarke]

@misi9170 We can close this issue, right? I think this has been addressed

[misi9170]

@misi9170 We can close this issue, right? I think this has been addressed

@genevievestarke agreed, this is addressed in #76 and used in #104, and this can be treated as complete.