Add schema tests for encoding fields.

Author: handrews

tests/schema/pass/media-type-examples.yaml

@@ -98,3 +98,13 @@ paths:
               forCoverage2:
                 style: spaceDelimited
                 explode: true
+          multipart/related:
+            schema:
+              type: array
+            itemEncoding:
+              contentType: text/plain
+            prefixEncoding:
+            - headers:
+                Content-Location:
+                  schema:
+                    type: string