Add UI feedback for OMEMO gen command

src/command/cmd_funcs.c

@@ -7898,6 +7898,7 @@ cmd_omemo_gen(ProfWin *window, const char *const command, gchar **args)
 
     ProfAccount *account = accounts_get_account(session_get_account_name());
     omemo_generate_crypto_materials(account);
+    cons_show("OMEMO crytographic materials generated.");
     return TRUE;
 #else
     cons_show("This version of Profanity has not been built with OMEMO support enabled");