Auto-targeting via AI

**Is your feature request related to a problem? Please describe.**
It would be nice to optionally pre-select targeting during SpellAbility activation. The selection isn't locked in of course, but it would speed up choices, especially when its a basic choice like "Target player" when its something you usually would choose a specific player.

Auto choices would be highlighted, but not necessarily selected. If the AI didn't know how to process targets, nothing would be highlighted. This might happen for Remove AI cards, or if for one reason or other AI wasn't feeling up to the task

**Describe the solution you'd like**
During spell casting, highlight objects that would potentially be targeted. An unused input button would be used to accept auto targets. If you start selecting other targets, the auto-targeting highlighting would be cleared.