[FEATURE]: Custom folder / password icon

[Arcesilas]

⚠️ This issue respects the following points: ⚠️

• This is a feature request for one feature, not a question, discussion or multiple features.
• This is not a feature request for the browser extension or another client.
• This feature is not already requested on Github (I've searched it).
• This feature does not already exist (I checked the wiki).

Current Status

Currently, folders have a basic folder icon and Passwords have automatically fetched favicon (when it works).
In some cases, passwords do not relate to any web site or any favicon (ssh login, email with no webmail).

Feature Description

1. I open the app
2. I click "..." to open the "New password" or "New folder" popup
3. Among other informations, I can choose a custom icon to upload
4. Folder or password entry now use my custom icon

Additional Context

No response