Fix GameTicker and StartingGear performing bad string checks.

- This prevented people from spawning as clown, etc if they had set the skirt option.
- Adds some custom type serializers to StartingGear for YAML linter support.

Content.Server/GameTicking/GameTicker.Spawning.cs

@@ -193,7 +193,7 @@ namespace Content.Server.GameTicking
                 foreach (var slot in EquipmentSlotDefines.AllSlots)
                 {
                     var equipmentStr = startingGear.GetGear(slot, profile);
-                    if (equipmentStr != string.Empty)
+                    if (!string.IsNullOrEmpty(equipmentStr))
                     {
                         var equipmentEntity = EntityManager.SpawnEntity(equipmentStr, entity.Transform.Coordinates);
                         inventory.Equip(slot, equipmentEntity.GetComponent<ItemComponent>());