objstorage_checker: Add support for consuming content ids from journal

Add ObjectStorageCheckerJournal class to consume content ids from a kafka topic in order to check their presence in a given object storage but also to check their integrity by fetching their bytes and recomputing checksums.

Related to #4694 (closed).

swh/scrubber/interface.py

-# Copyright (C) 2024  The Software Heritage developers
-# See the AUTHORS file at the top-level directory of this distribution
-# License: GNU General Public License version 3, or any later version
-# See top-level LICENSE file for more information
-
-
-from typing_extensions import Protocol, runtime_checkable
-
-from swh.core.statsd import Statsd
-
-from .db import ConfigEntry, Datastore
-
-
-@runtime_checkable
-class CheckerInterface(Protocol):
-    @property
-    def config(self) -> ConfigEntry:
-        ...
-
-    @property
-    def datastore(self) -> Datastore:
-        ...
-
-    @property
-    def statsd(self) -> Statsd:
-        ...
-
-    def run(self) -> None:
-        ...