Support metadata mask for feature score eviction (#3277)

Summary:
Pull Request resolved: #3277

As title, in feature score eviction policy, the 31 bit count in metaheader is float type. Need to handle it in parse util func.

Reviewed By: emlin

Differential Revision: D80131015

fbshipit-source-id: d295c5db9cf53c6f8c6a62c82b5ac5eeef777980

Author: EddyLXJ

torchrec/modules/embedding_configs.py

@@ -219,6 +219,13 @@ class FeatureScoreBasedEvictionPolicy(VirtualTableEvictionPolicy):
     decay_rate: float = 0.99  # default decay by default #TODO: Change to real value
     max_training_id_num_per_rank: int = 0  # max number of training ids per rank
     target_eviction_percent: float = 0.0  # target eviction percent
+    inference_eviction_feature_score_threshold: Optional[float] = (
+        None  # 0 means no eviction
+    )
+
+    def __post_init__(self) -> None:
+        if self.inference_eviction_feature_score_threshold is None:
+            self.inference_eviction_feature_score_threshold = 0
 
 
 @dataclass