Change Replacements Treatment

[adfarth]

• ElectricStorage and Generator have replacement_year inputs. It is assumed that these two technologies can be replaced within the analysis period.
• Previously, replacement costs were treated as tax deductible. Neither ITC nor MACRS were applied to these costs.
• Now, we are treating replacement costs are depreciable and are applying the ITC and MACRS to these costs.
• The following new inputs have been added to ElectricStorage and Generator:
  -- replace_macrs_option_years
  -- replace_macrs_bonus_fraction
  -- replace_total_itc_fraction
• For Generators, we assume no ITC or MACRS incentives for the upfront cost or replacements
• For ElectricStorage replacements, we assume that the MACRS bonus depreciation has phased out, that storage qualifies for 5-year depreciation (2025 and onward), and that the ITC remains at 30%.
• This is all captured in the effective_cost() calculation

TODO:

• Update CHANGELOG
• Add tests
• Update reporting of results (esp. in financial.jl and proforma.jl)
• Update existing tests once this branch is fully tested
• Consider changing input names to "replacement" not just "replace"?
• Also update docs?
• Check if generator replacement costs apply to total capacity or just new

Note! I haven't looked into tax treatment assumptions built into replacement costs with battery degradation modeling.

[adfarth]

Added all of this as in-line conditional statements below

[adfarth]

I'm not sure why we previously defaulted this to 1. It got set to 0 anyway (in cost_curve.jl) since macrs_option_years = 0.

[adfarth]

I made this a separate function so we can just call this to get replacement costs in the reporting of results.