Migrate and overhaul heal event and heal amount expression

[MrScopes]

Problem

Currently, heal uses a utility that just set's their health to their current health + the heal amount
this does not call EntityRegainHealthEvent
Also, in the EntityRegainHealthEvent it doesn't take into account Skript using health (10 hearts) instead of hp (20hp), so heal-amount is hp and not hearts.
This is inconsistent with the rest of the code base.
Also, migrating the current system to the new module system.

Update HealUtils to use Damageable.heal instead of setHealth
The reason this was made in the first place is because Spigot has never and still doesn't have a Damageale.heal but now that Skript is paper only, this is appropriate

Testing

currently, heal amount tested with

on heal:
    broadcast "hp: %player's health%"
    broadcast "initial heal amount: %heal amount%"
    add 1.5 to heal amount
    broadcast "add 1.5: %heal amount%"
    remove 3.2 from heal amount
    broadcast "remove 3.2: %heal amount%"
    set heal amount to heal amount * 0.75
    broadcast "set to 75%%: %heal amount%"
    broadcast "modified heal amount: %heal amount%"
    chance of 50%:
        delete heal amount
        broadcast "deleted heal amount: %heal amount%"
    wait 1 tick
    broadcast "hp after heal: %player's health%"

here's the current test for the heal event as well

command /heal:
    trigger:
        heal player by 0.5
        wait 1 tick
        heal player by 0.75
        wait 1 tick
        heal player by -3
        wait 1 tick
        heal player by 1
        wait 1 tick
        heal player by 1500.23
        wait 1 tick
        heal player by 100000000000000
        wait 1 tick
        heal player by -10000

on heal:
    broadcast "heal %entity% %heal amount%"

on damage:
    broadcast "damage %victim% %damage%"

migrated heal reason test

on heal of player:
    broadcast "heal %player% %heal amount% %heal reason%"

---

Completes: none
Related: none
AI assistance: none

[erenkarakal]

tests failing

[MrScopes]

tests failing

ahh that's because I didn't account for skript using health and not hp

[MrScopes]

I'm changing the scope of this pr to migrate exprhealreason, exprhealamount, and heal event to player module
also fixing the bug of using hp and not hearts that skript currently has
and of course still updating HealUtils to use Damageable.heal instead of setHealth

[AnOwlBe]

I already migrated this (https://github.com/SkriptLang/Skript/pull/8748/changes#diff-5dc1b4cdab125cd303ada3ff87ae57c8026a98762768cc6f91529578a372787c) so probably no reason to also migrate it here