Describe the feature

For players/self it is helpful to see only health loss. For enemy targets, I care more about how much health is left. It would be helpful to have an option to invert the target health bar appearance.

Describe the implementation

Add an option to invert health bar appearance for target (and focus) unit frames for enemy units. For players I want health loss to be the filled color, but for enemy units, I want the remaining health to be the filled color. That way, the important info about each unit is the filled color (ex. how much do I need to heal and how much enemy HP to burn).