Make underlying results of SignEncryptTask accessible
Make the result class SignEncryptTaskResult of SignEncryptTask public
so that one can access GpgME's result classes. This will be used to
check for invalid recipients in the encryption result.
(cherry picked from commit 7939a9a0ed1d5505893455327a65814485aa174f)
- GnuPG-bug-id: T6702