Zombie Improvements

This mod improves zombie leader and reinforcement mechanics and fixes a few bugs with them.

What?

If you didn't even know these were a thing, here's a rundown from the Minecraft wiki:

On all difficulty levels, damaged zombie mobs (including husks, drowned and even zombified piglins) call all other zombies within a 67×21×67 to 111×21×111 area centered on the attacked zombie to target the attacker.

In Hard difficulty, zombies can spawn additional zombies to "help" when damaged. Each zombie has a "likeliness to call reinforcements" statistic ranging from 0–10%, and "leader" zombies (0–5% depending on regional difficulty) get a bonus of 50–75 percentage points to the stat.

On Hard difficulty, zombies have a 5% chance to spawn as leaders. Leader zombies can spawn other zombies as reinforcements.

So what does this mod do?

There are a few issues with these mechanics:

• You can't tell if the zombie you're attacking is a leader or not.
• There is no visual/audio cue when zombies spawn additional reinforcements.
• There are a few bugs which make these mechanics less relevant.

This mod alleviates all of these issues by:

• Adding a red aura effect around leader zombies, identical to the charged creeper effect, but red color.
• Adding a sound that plays when a zombie spawns in additional reinforcements. The sound that will be played is the block breaking sound of the block the freshly spawned zombie is standing on, played 5 times in a span of 2 seconds.
• Fixing two vanilla bugs, namely MC-219981 and (1.21.1 only) MC-14800.

There's also a few additional tweaks, disabled by default:

• Allow only leader zombies to spawn additional reinforcements.
• Prevent mob spawners from spawning leaders.
• Prevent zombies spawned by mob spawners from spawning additional reinforcements.