[Suggestion]: allow user-selected icon for password entries

[umlaeute]

Suggestion

currently, passy uses the website-field of an entry to retrieve the favicon and display this as the entry's icon.

i dislike this for various reasons:

• one of my sites (with a site-specific username/password) - e.g. https://example.org - has many subdomains (e.g. https://git.example.org) where i can use the same username/password. however the website for the domain itself redirects to another domain (we are a subdivision of a larger organization with our own user management). i do not want to see the con of the parent organization
• afaict, the icon is not cached at all, and instead it is queried live from all the webpages.
  • this creates useless traffic, only for icons
  • this exposes the mere fact that i'm opening up passy to all the websites that i have stored passwords for
• oftentimes the favicon is rather generic (probably not an issue with the big companies; but more with self-hosted sites)
• sometimes that favicon is just ugly :-)

it would be nice, if instead i could provide a png with the icon myself:

• looks like i want it to look like
• less pricacy issues

Submission checklist

• I have specified my suggestion in the issue title

[umlaeute]

so far, i have no preference whether manual icons should be synched between devices.