GHP Cost Curve Fix for ton-based rebates

[Bill-Becker]

The ITC and MACRS were not getting applied to the GHX and other non-heat-pump components, so as a workaround to shift the bug into a much less used component (rebates based on heat pump tonnage), all of the cost was lumped into the heat pump capacity-based term of the 2 term cost curve. So currently the rebates will be overestimating savings because they will apply to all GHP and GHX, etc components. To fix this for the long term solution, we need to migrate this function from the API and other related changes from that commit to separately apply the %-based incentives like ITC, and MACRS to the y-intercept term for GHX, etc components:

https://github.com/NREL/REopt_API/blame/c971e014bff491d4b665af308f7c7a207dc9f0ff/reo/src/data_manager.py#L320