Add LoggingData annotation to Logger base import so users can type-annotate Logger subclasses properly.
from acme.utils.loggers.aggregators import Dispatcher
from acme.utils.loggers.asynchronous import AsyncLogger
from acme.utils.loggers.base import Logger
+from acme.utils.loggers.base import LoggingData
from acme.utils.loggers.base import to_numpy
from acme.utils.loggers.csv import CSVLogger
from acme.utils.loggers.filters import NoneFilter
