Add HTTP ShapeSerializer

Author: JordonPhillips

packages/smithy-core/src/smithy_core/traits.py

@@ -271,7 +271,7 @@ def __post_init__(self):
         assert isinstance(self.document_value, str)
 
     @property
-    def name(self) -> str:
+    def key(self) -> str:
         return self.document_value  # type: ignore