Function register_file_source 

pub fn register_file_source(
    registry: &ConnectorRegistry,
) -> Result<(), ConnectorError>

Registers the file source connector in the registry.

This is called by LaminarDB::register_builtin_connectors() when the files feature is enabled, and makes FROM FILES (...) available in CREATE SOURCE statements.

Errors

Returns an error if the connector name is already registered or the registry is frozen.