Spells with multiple damage types aren't represented

Taking the spell Ice Storm for example:

Ice Storm is an AoE spell that deals (at base level) 2d8 bludgeoning damage + 4d6 cold damage. The API lists the spell damage as follows:

```
"damage": {
"damage_type": {
"index": "bludgeoning",
"name": "Bludgeoning",
"url": "/api/damage-types/bludgeoning"
},
"damage_at_slot_level": {
"4": "2d8 + 4d6",
"5": "3d8 + 4d6",
"6": "4d8 + 4d6",
"7": "5d8 + 4d6",
"8": "6d8 + 4d6",
"9": "7d8 + 4d6"
}
},
```

It correctly captures that two different damage types are used for the respective d8 and d6 rolls. But does not identify the damage type and also missed the cold damage type altogether.

Not sure the optimal representation for this, but I suggest the keys for "damage_at_slot_level" and "damage_at_character_level" to be a subtype of "damage_type". Additionally "damage_type" would replace the current "damage" key, as "damage" seems redundant since I believe there are no times where a damage value exists without belonging to a damage_type Resulting in this instance for the below fix for Ice Storm

```
"damage_type": [
{
"index": "bludgeoning",
"name": "Bludgeoning",
"url": "/api/damage-types/bludgeoning",
"damage_at_slot_level": {
"4": "2d8",
"5": "3d8",
"6": "4d8",
"7": "5d8",
"8": "6d8",
"9": "7d8 "
}
},
{
"index": "cold",
"name": "Cold",
"url": "/api/damage-types/cold",
"damage_at_slot_level": {
"4": "4d6",
"5": "4d6",
"6": "4d6",
"7": "4d6",
"8": "4d6",
"9": "4d6"
}
}
],
```