[Feature Request] Save Archetype progress when switching

Currently, when switching archetypes, progress is not saved. If you then switch back to that archetype, your progress is reset to zero.

Example:

Archetype Warrior and Archer in the group CLASS. If you start as a Warrior and, for example, get to level 4 and then switch to Archer and back to Warrior, the level is 1.

If you look at the data JSON you can see that the progress from Warrior is gone after switching to Archer.

Data after bringing the Warrior to level 4 (in MythicRPG/data/players/):

"CLASS": {
      "Warrior": {
        "archetypeId": "Warrior",
        "level": 4,
        "experience": 200,
        "targetExperience": 1000,
        "source": "GENERAL",
        "sourceData": "HugoHuetzel",
        "description": "[]",
        "unlocked": true
      }
    }

Data after switching to Archer:

"CLASS": {
      "Archer": {
        "archetypeId": "Archer",
        "level": 2,
        "experience": 100,
        "targetExperience": 600,
        "source": "GENERAL",
        "sourceData": "HugoHuetzel",
        "description": "[]",
        "unlocked": true
      }
    }

It would be great if the data wasn't deleted/overwritten when switching.