Option to set custom icons or select from a built-in icon database for vault items

Hi everyone,

First of all, thank you for all the great work on Vaultwarden!

Currently, Vaultwarden automatically fetches website favicons for items based on their URLs. While this works well in most cases, some websites do not provide a proper favicon, or the system fails to fetch them. Additionally, for internal/local service entries without public domains, icons often remain default or empty.

Would it be possible to consider adding a feature to:
1. Allow users to upload custom icons (e.g., custom images/PNGs/SVGs) directly to an item.
2. Or provide a built-in icon library/database (such as Simple Icons or FontAwesome) so users can manually select an icon for an entry.

Having this feature would greatly improve organization and visually customize the vault.

Thanks for considering this request!