Create a new Service proxy for the Secret Service.
This function is rarely used, see [funcService.get] instead.
The service_gtype argument should be set to SECRET_TYPE_SERVICE or a the type of a derived class.
If flags contains any flags of which parts of the secret service to ensure are initialized, then those will be initialized
before returning.
If service_bus_name is null then the default is used.
This method will return immediately and complete asynchronously.
| service_gtype |
the GType of the new secret service |
| service_bus_name |
the D-Bus service name of the secret service |
| flags |
flags for which service functionality to ensure is initialized |
| cancellable |
optional cancellation object |
| callback |
called when the operation completes |
| user_data |
data to be passed to the callback |