Clean up power plant construction at fuel-generation process level

[dt-woods]

Along with the new regionalized renewable power plant construction processes are a few instances with multiple plant types, such as wind and solar PV plant construction for Arizona Public Service Company's wind generation (see screenshot).

There should be only one construction input to these processes (for fuels that are not labeled as 'OTHF' or 'MIXED') and the construction plant type should match the fuel category.

[dt-woods]

A potential cause of this "cross pollination" may be caused by regions (e.g., balancing authority areas) where the only solar generation is occurring at a coal or natural gas facility. This may be what's putting solar PV and coal together.