Add Error Messages to the Downgrade Ritual

[VT-14]

This gives clear indications to the player about what is going wrong for the most commonly seen issues.

• A Training Bracelet is blocking the Downgrade.
• The player doesn't have enough of the Key Item (message appears if what they already have is >= what is in the chest, most likely they have level 1 and only 1 Key item in the chest).
• The player doesn't have enough Upgrade Points in the chest to apply the Downgrades they are requesting.
• The inventory to hold the downgrade recipe is missing.