Describe the feature

For example, when you cast a heal on a player, the name of the player is also shown on the castbar.
The same if you cast damage on an enemy.
Preferably with options for player- and enemy-name.

Describe the implementation

This has now been implemented - The option for Player/Enemy won't be implemented since the only reliable source of a target name is this event UNIT_SPELLCAST_SENT which only provides a name and not a Unit, so whether it's friendly or not can't be easily determined.