Add action for refreshing (multiple) keys to key list
As part of this, the RefreshCertificateDialog is adapted to refreshing multiple keys. Showing correct results for this proved tricky - both in implementation and UX, as there are many potential outcomes. The intended UX is roughly:
- If only one key is refreshed, the command should behave as it did previously
- If multiple keys are refreshed, errors are shown, while also showing if the "other" job (smime or pgp) has succeeded.
- If multiple keys are refreshed, exact information like "key was not found" and "key was not changed" is not shown.
GnuPG-Bug-ID: 6739