[Suggestion] add new action stack target that targets the party member with lowest health

[jundong321]

As the title suggests, add a new action target that targets the party member with lowest health. It can help single target heals, and it might work very well because most of the single target heal will be targeting the party member with lowest health. Some custom logic of comparing health of all party members will be needed for this.

[jundong321]

We can probably use Partylist and PartyMember.