LDES project updates

[hdunham]

Develop LDES

Added

• Added inputs om_cost_per_kw and om_cost_per_kwh to ElectricStorage for modeling capacity-based O&M
• Added outputs lifecycle_om_cost_after_tax and year_one_om_cost_before_tax to ElectricStorage
• Added new input self_discharge_fraction_per_timestep to ElectricStorage for modeling battery self-discharge
• Added input option can_export_to_grid (defaults to false) to ElectricStorage and decision variable dvStorageToGrid
• Added input fixed_duration to ElectricStorage, which fixes the ratio between size_kw and size_kwh in the optimized solution if provided
• Added input option optimize_soc_init_fraction (defaults to false) to ElectricStorage, which makes the optimization choose the inital SOC (equal to final SOC) instead of using soc_init_fraction. The initial SOC is also constrained to equal the final SOC, which eliminates the "free energy" issue. We currently do not fix SOC when soc_init_fraction is used because this has caused infeasibility.
• Added output initial_capital_cost to all techs
• Added ability to model multiple ElectricStorage at once. Inputs are provided as a list of dict under the ElectricStorage key and outputs are similarly formatted. This mirrors the existing multiple PV implementation. This functionality is not yet implemented for MPC scenarios.

Fixed

• Added missing outputs lifecycle_export_benefit_before_tax and year_one_export_benefit_after_tax to ElectricTariff
• Add missing output year_one_om_cost_before_tax to PV

[adfarth]

@hdunham I'm seeing some discrepancies and overlap between this branch and:

• https://github.com/NREL/REopt.jl/pull/354/files -- for the ElectricStorage O&M changes by @lixiangk1. Is that PR or this PR more up-to-date for those changes?
• Limit battery storage duration #332 -- for the ElectricStorage min, max duration inputs by @atpham88, which is an alternative way to implement the fixed_duration changes in this branch.

I think it makes sense to merge each of those branches above into this PR. What do you think?