Allow revoking key certifications.

Certified user identities in keys can be revoked using the same popup
for certification.

Requires GnuPG 2.2.24 (not available in distro's repository, not fully
tested to date).

GpgMEWorker.h

@@ -77,6 +77,19 @@ public:
                            const char * fprKeyToSign,
                            vector<uint>& userIDsToSign, int options,
                            const string& passphrase);
+    /**
+     * Revoke UserID certifications.
+     * \n Requires GnuPG >= 2.2.24
+     * @param fprSigningKey
+     * @param fprKeyToSign
+     * @param userIDsToRevoke : vector of ::UserID
+     * @param passphrase
+     * @return 
+     */
+    const Error RevokeKeyCertifications(const char * fprSigningKey,
+                           const char * fprKeyToSign,
+                           vector<GpgME::UserID>& userIDsToRevoke,
+                           const string& passphrase);
     /**
      * Sets the expiry time of a single subkey. Requires GPGME >= 1.15.0.
      * \n If no subkey is found (wrong fpr), the expiry time of key is set