Feature Request: Activation Tokens for Custom Models

With the new support for custom models there should be some way to manage the custom activation token for each model. For example the popular [midjourney-v4-diffusion](https://huggingface.co/prompthero/midjourney-v4-diffusion) needs `mdjrny-v4 style` added to the prompt for the model to be useful. Each custom model has a different 'activation token' it needs. Currently I have a text document with these listed but it's quickly getting out of hand.

There should be a way to associate an activation token with a custom model. Perhaps the needed token for a currently selected model could be shown as a suggestion at the top of the list of styles