add ForceKill action type for MythicMobs vanilla override support

[JrouleEnGolf5]

Problem

When MythicMobs applies a vanilla override to a base Minecraft mob (e.g. a Zombie configured to drop a diamond), the mob becomes invisible to both existing kill actions:

• Kill skips it because isMythicMob() returns true
• MMKill skips it because the mob has no custom MythicMobs internal name

Players receive no job reward when killing vanilla-override mobs.

Solution

Adds a new ForceKill action type that bypasses the MythicMobs check and always fires on entity death, matching by vanilla entity type name (same as Kill).

Changes

• ActionType.java — added FORCEKILL enum entry
• JobsPaymentListener.java — KILL is gated behind !isMythicMobEntity, ForceKill always dispatches

No impact on existing Kill or MMKill configurations.