Detect new credentials in Apps and offer to store them

When entering a login/password into a website in browser, KeepassDX pops up a dialog and offers to store the new login.
If I do the very same thing in random Android Apps, KeepassDX does not ask me to store the login. I tested this with multiple Apps.

Since keepassDX autofill works just fine in Android Apps, if the AppID is used for matching URL it would be nice, if it also worked to create these entries. Ideally it would also let me choose an existing entry to add a 2nd URL using KP2A_URL fields.

Start from the existing Android autofill flow, which already matches AppIDs for filling credentials. Trace how credentials are detected in apps and how an existing entry could receive a second KP2A_URL field. Done means new app credentials prompt for storage and can be added to an existing entry with the appropriate URL.

Written by the indexing model from the issue text.