Add test for map of sets to restJson protocol test.

Author: kggilmer

smithy-aws-protocol-tests/model/restJson1/json-maps.smithy

@@ -286,6 +286,8 @@ structure JsonMapsInputOutput {
     sparseNumberMap: SparseNumberMap,
     sparseBooleanMap: SparseBooleanMap,
     sparseStringMap: SparseStringMap,
+    denseSetMap: DenseSetMap,
+    sparseSetMap: SparseSetMap,
 }
 
 map DenseStructMap {
@@ -325,3 +327,14 @@ map SparseNumberMap {
     key: String,
     value: Integer
 }
+
+map DenseSetMap {
+    key: String,
+    value: aws.protocoltests.shared#StringSet
+}
+
+@sparse
+map SparseSetMap {
+    key: String,
+    value: aws.protocoltests.shared#StringSet
+}