Include bifaciality effect in ML module model

[timorichert]

Is your feature request related to a problem? Please describe.
Currently, the ML model does not consider bifaciality effects.

Describe the solution you'd like
The backside irradiance should be considered in the effective irradiance sum considering the bifaciality factor, as already implemented in the CEC module model.

[caseyzak24]

@timorichert this is an important feature for us as well. Are you already working on it? If not I will start but I don't want to duplicate efforts.

[caseyzak24]

@timorichert just for reference this would be addressed by a commit I submitted as part of PR #314

[timorichert]

@caseyzak24 great work and thanks for the effort! I'm currently not working on anything SAM-related, but love to see the current developments!

[allenlawrence94]

Addressed here: #622