Refactors ERM, Misc build_powerplants parameter fixes, and plant assignments

[ktehranchi]

Changes proposed in this Pull Request

• Refactors the Energy Reserve Margin (ERM) opt to vectorize constraint creation, adds test case for multi-region reserves
• Unit-commitment Parameters for thermal plants were incorrectly imputed by taking averages over the wrong fields. This lead to mixing of variable fuel cost based parameters from fixed start-up fuel consumption parameters.... tldr some OCGTs had way to large of start-up costs which are now fixed.
• user @mailyorlik identified plants which were mis-assigned BA due to imprecise ReEDS shapes. I added some logic here that should fix this issue to ensure plants at the edges of interconnections (EROCT/EI) are not mis-aligned. But at the seams of balance authorities within an interconnection, this issue likely still persists and will need to be addressed.

Checklist

• [ ] I tested my contribution locally and it seems to work fine.
• [ ] Code and workflow changes are sufficiently documented.
• [ ] Changed dependencies are added to envs/environment.yaml.
• [ ] Changes in configuration options are added in all of config.default.yaml.
• [ ] Changes in configuration options are also documented in doc/configtables/*.csv.