feat(skymp5-server): implement EquipSpell Papyrus native

[Pospelove]

[!IMPORTANT] Adds EquipSpell method to PapyrusActor for equipping spells, with argument validation and registration.

• Behavior:
  • Adds EquipSpell method to PapyrusActor to equip spells, checking for valid arguments and spell type.
  • If the spell is not in the actor's spell list, it adds the spell.
• Logging:
  • Logs errors for invalid arguments and spell types in EquipSpell.
• Registration:
  • Registers EquipSpell method in PapyrusActor::Register.

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