ExperienceOrbs API for Reason/Source/Triggering player

Adds lots of information about why this orb exists.

Replaces isFromBottle() with logic that persists entity reloads too.

paper-server/patches/sources/net/minecraft/world/entity/LivingEntity.java.patch

@@ -805,7 +805,7 @@
 +    protected void dropExperience(ServerLevel world, @Nullable Entity attacker) {
 +        // CraftBukkit start - Update getExpReward() above if the removed if() changes!
 +        if (!(this instanceof net.minecraft.world.entity.boss.enderdragon.EnderDragon)) { // CraftBukkit - SPIGOT-2420: Special case ender dragon will drop the xp over time
-+            ExperienceOrb.award(world, this.position(), this.expToDrop);
++            ExperienceOrb.award(world, this.position(), this.expToDrop, this instanceof ServerPlayer ? org.bukkit.entity.ExperienceOrb.SpawnReason.PLAYER_DEATH : org.bukkit.entity.ExperienceOrb.SpawnReason.ENTITY_DEATH, attacker, this); // Paper
 +            this.expToDrop = 0;
 +        }
 +        // CraftBukkit end