Using EmbeddingPlannerBase for all planner implementations (#3232)

Summary:

As title

Reviewed By: aporialiao

Differential Revision: D78887917

Author: aliafzal

torchrec/distributed/planner/__init__.py

@@ -21,6 +21,9 @@
     - automatically building and selecting an optimized sharding plan.
 """
 
-from torchrec.distributed.planner.planners import EmbeddingShardingPlanner  # noqa
+from torchrec.distributed.planner.planners import (  # noqa  # noqa
+    EmbeddingPlannerBase,
+    EmbeddingShardingPlanner,
+)
 from torchrec.distributed.planner.types import ParameterConstraints, Topology  # noqa
 from torchrec.distributed.planner.utils import bytes_to_gb, sharder_name  # noqa