Register GRF-based ATT estimator in the estimator registry

This compatibility helper attempts to register est_grf_dr_att under the ID grf_dr_att. Current releases already ship that optional descriptor, so ordinary use should call the estimator through the runner and does not need this helper. Like any duplicate registration, calling it when the ID is already present aborts with causalstress_registry_error.

Usage

cs_register_grf_dr_att()

Value

Invisibly, the updated estimator registry.