Add fused_params to mch sharders (#1649)

Summary:

This diff is not really ideal. Ideally we can deprecate the sharder fused params path.

The question is which one would happen first:
1. zch + uvm caching
2. the use of per table CLF.

Differential Revision: D52921362

Author: henrylhtsang

torchrec/distributed/mc_embedding_modules.py

@@ -6,7 +6,7 @@
 # LICENSE file in the root directory of this source tree.
 
 import logging
-from typing import Dict, Iterator, List, Optional, Tuple, Type, TypeVar, Union
+from typing import Any, Dict, Iterator, List, Optional, Tuple, TypeVar, Union
 
 import torch
 from torch.autograd.profiler import record_function
@@ -276,3 +276,8 @@ def sharding_types(self, compute_device_type: str) -> List[str]:
                 set(self._mc_sharder.sharding_types(compute_device_type)),
             )
         )
+
+    @property
+    def fused_params(self) -> Optional[Dict[str, Any]]:
+        # TODO: to be deprecate after planner get cache_load_factor from ParameterConstraints
+        return self._e_sharder.fused_params