Function set_backend_log_severity 

pub fn set_backend_log_severity(
    severity: Severity,
) -> Result<(), TransportError>

Set the verbosity of every registered BACKEND’s own logging.

This is the backend’s logger — Cyclone’s dds_log, zenoh-pico’s — not nros_log, which is the runtime’s and is set directly through nros_log::Logger::set_level with no ABI involved.

Applies to EVERY registered backend, because an image may link more than one (nros_rmw_cffi_register_named) and verbosity is a property of the process rather than of a session. Upstream has no equivalent decision to make: it loads one implementation.

Returns Unsupported when no registered backend implements the slot, the first error any backend reported otherwise, and Ok when at least one accepted it.