Function get_authorization_for_route_table 

pub async fn get_authorization_for_route_table<I: Ip + FidlRouteAdminIpExt + FidlRouteIpExt>(
    route_table: &<I::RouteTableMarker as ProtocolMarker>::Proxy,
) -> Result<GrantForRouteTableAuthorization, Error>

Dispatches get_authorization_for_route_table on either the RouteTableV4 or RouteTableV6 proxy.