Add comfort envelope to psychrometric chart

[mccalluc]

The original issue drifts, but adding a comfort envelope is proposed in https://github.com/CenterForTheBuiltEnvironment/clima/issues/83#issuecomment-1322530903. There are a lot of choices here, and I'm not sure it's even a feature you want.

• What definition of the envelope would you want?
• Would we want to show multiple? Allow the user to select between some choices?
• How should it be presented? This is just the default -- Lines and colors could change.
• Do we want anything in the legend?

Filing as draft.

(Just noticed #116 as well -- There are a lot of possibilities, and, as noted there, this isn't the highest priority.)