[FEAT] Calculate the electron temperature

[aaronjridley]

Is your feature request related to a problem? Please describe. The electron temperature needs to be calculated.

Describe the solution you'd like Once the collisional heating terms are calculated, there is still a LONG way to go on the electron temperature. This has a HUGE number of terms and is very complicated. We need to calculate this much more carefully than in the past, since the code in GITM is just spaghetti.

Describe alternatives you've considered Can put in an approximation to begin with.

Additional context Zhu and Ridley describe the method for the electron temperature equation. GITM's code works.