Move more cmods to the attic

[brtietz]

Code coverage indicated a number of cmods that could stand to be moved to the attic. The list so far is:

-cmod_fossilgen.cpp
-cmod_utilityrate(1-4).cpp

Flesh out this list and move these to the attic for the next release

[janinefreeman]

I don't see any other obvious ones to move (to me), but would appreciate if @tyneises would check that there aren't any old/unused csp compute modules hanging around. Thanks!

[brtietz]

Partially solved with #1297. I believe there is a CSP attic PR coming, so leaving this open for now as a reminder.

[tyneises]

CSP clean up here #1299 and here NREL/SAM#2037