show error message when we try to connect anonymously to a server that doesn't support anonymous connection. Fixes #8138

correctly detect that key is not trusted before encrypting. Doc says: "gpg just prints a message to the console, but does not provide a specific error indication that the Python wrapper can use." Fixes #8040. See #8041

if config file says password is saved with libsecret (with py3 branch) we can still get it with gnomekeyring