Follow up of T7128.

In the upper part of the certificate details window there is a line starting with "Private Key:" just above the tabs.

The info here is misleading if not all subkeys are stored in the same location.
See e.g. the picture below, where the primary key was moved to a smart card and deleted on disk, but the subkey is still on disk:

It seems only the storage location of the primary key is taken into account.

I propose to only show the storage location in this place if all subkeys have the same one. Otherwise we could display a helpful hint. Some possibilities:

• Private Key: Check subkey storage locations
• Private Key: Ambiguous, check subkey locations
• Private Key: Subkeys stored in different places

An other possibility would be to get rid of the "Private Key: " info field altogether. Most of its information is available in the storage column of the subkeys tab. Which is of course less discoverable. And does not contain any information regarding duplicate existences of a key on disk and on smart card(s). ("On this computer and on a smart card")