Add an option to include any hardcasting resource gains in logic determining if the bar color should change to denote an ability is usable (e.g. Insanity and DP).

Considerations/notes:

• Opt in only. Default behavior will remain.
• Should this apply to threshold lines as well? Different color?
• Which specs to include.

Originally posted by @stopskii in #206 (comment)

In Priest.lua I suggest altering line 4233 so that 'currentInsanity' is instead 'castingBarValue'.
This way the insanity casting bar changes color if devouring plague will be cast-able after the current cast is complete.
This will make it slightly functionally different than the already implemented "insanity when you can cast Devouring Plague", as currently these two are both using the current insanity to determine when to alter the color, but I feel altering the hard cast incoming insanity color code to account for whether DP is castable after finishing that current hard cast makes more sense.

This might end up being something tackled when I address some combination of #152 and #163. TBD.