Make mobs alert other mobs when target found

[Arcanorum]

Task description

It is currently too easy to pick off single mobs that are in a group and lure them away.

It would be better if when a mob notices a target (another character type of an opposing faction) then it would broadcast that information to any other mobs of the same faction within a certain range, so they too would be alerted of the target being found.

For example:
There is a group of knights near each other facing in different directions.
A bandit moves into the view range of a knight, so the knight notices it.
The knight would check for all nearby knights (and any other characters that have a friendly faction relationship to the knight) and tell each one of them to focus on the bandit (if they don't already have a target).

References/notes

Character factions: https://github.com/Arcanorum/dungeonz/blob/master/server/src/gameplay/Factions.js
Mob logic: https://github.com/Arcanorum/dungeonz/blob/master/server/src/entities/classes/destroyables/movables/characters/mobs/Mob.js

• See onDamage for what the mob should do when it is damaged.
• See getNearestHostileInLOS for when a hostile character is found by this mob.

Try with a range of 4 (in all directions) to check for other friendly mobs, though this may change depending on testing/feedback, as long as it is configurable.

Acceptance criteria

• When a mob is damaged, it should check the source of the damage and if it is another character, then it should target that character, and also check for characters of a friendly faction within a 4 tile radius that do not have a target and set their target to the damaging character.
• When a mob finds a character of a hostile faction, it should target that character, and also check for characters of a friendly faction within a 4 tile radius that do not have a target and set their target to the hostile character.
• The 4 tile radius should be added as a property to the Mob prototype, something like alertRange.

[Sebasflow23]

Zombie pigmen flashbacks.