mutation enchantment item fix

[KorGgenT]

Summary

SUMMARY: Bugfixes "Fixes relic enchantments giving mutations"

Purpose of change

Fixes #42936

Describe the solution

adds a new item::mutations_from_wearing and invokes that in Character::on_wear, while also checking that you don't gain double effects.

Testing

  {
  "id": "Wildshape Cloak: Fish",
  "type": "ARMOR",
  "name": "Wildshape Cloak: Fish",
  "description": "A magical cloak that shimmers like fresh water under a warm sun. It can be worn to morph your body to a form that is excellent for swimming, but ill-suited for combat.",
  "looks_like": "cloak_leather",
  "weight": "2060 g",
  "volume": "3050 ml",
  "price": 500000,
  "symbol": "w",
  "color": "blue",
  "covers": [ "torso", "arm_l", "arm_r", "leg_l", "leg_r" ],
  "coverage": 0,
  "encumbrance": 0,
  "flags": [ "OUTER", "OVERSIZE", "NONCONDUCTIVE", "WATER_FRIENDLY", "RAINPROOF" ],
    "relic_data": {
    "passive_effects": [
      {
        "has": "WORN",
        "condition": "ALWAYS",
        "mutations": [ "STR_UP" ]
      } 
    ]
  }
  },

Used this, and a variation of this with different mutations to test various mutations, such as gills and rubbery limbs

Additional context

Mutations gained from enchantments still don't cancel current mutations. i don't really want to deal with that in this PR, and it's somewhat amusing to me that you can get weak and strong at the same time in magiclysm. There's also a non-negligible amount of work needed to go into doing that, so that can be punted to a follow-up.