Reserve id range in _func space for SQL procedures

Current issue is a part of the SQL procedures track in picodata. We need to map picodata procedures into tarantool functions inside _func space to check procedure permissions (at the moment tarantool core checks all the permissions in picodata). So, the idea is to write into the raft log some dummy functions with ids equal to the procedure id in _pico_routine. These new ids must be reserved for picodata DDL on any instance and protected from local consumption with Lua API. In other words, we need some protected range for picodata in the _func space to use it only via C API with picodata DDL.