Fix NOx and SO2 adjustments

[grgmiller]

Purpose

In pre-2012 data, there are several data availability issues that may affect the quality of SO2 and NOx data:

• do we have boiler type data for nox calculations?
• EIA-923 emissions controls data: pre 2012
• do we have sulfur content data
• Missing fuel-PM-firing combinations in the NOX and SO2 factors

What the code is doing

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Testing

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Where to look

• It's helpful to clarify where your new code lives if you moved files around or there could be confusion/

• What files are most important?

Usage Example/Visuals

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Review estimate

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Future work

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Checklist

• Update the documentation to reflect changes made in this PR
• Format all updated python files using black
• Clear outputs from all notebooks modified
• Add docstrings and type hints to any new functions created