Currently, the runc shimv2 commandline manager doesn't support ttrpc
server's customized option, for example, the ttrpc server interceptor.
This commit is to allow the task plugin can return the
`UnaryServerInterceptor` option to the manager so that the task plugin
can do enhancement before handling the incoming request, like API-level
failpoint control.
Signed-off-by: Wei Fu <fuweid89@gmail.com>
