fix tests with formatting

crates/apollo-compiler/test_data/err/0001_duplicate_operatoin_names.txt

@@ -21,7 +21,7 @@
                 ),
             },
             help: Some(
-                "getName must only be defined once in this document.",
+                "`getName` must only be defined once in this document.",
             ),
         },
     ),

crates/apollo-compiler/test_data/err/0013_schema_definition_with_duplicate_root_type_operations.txt

@@ -21,7 +21,7 @@
                 ),
             },
             help: Some(
-                "customPetQuery must only be defined once in this document.",
+                "`customPetQuery` must only be defined once in this document.",
             ),
         },
     ),

crates/apollo-compiler/test_data/err/0021_union_definition_with_duplicate_members.txt

@@ -21,7 +21,7 @@
                 ),
             },
             help: Some(
-                "Photo must only be defined once in this document.",
+                "`Photo` must only be defined once in this document.",
             ),
         },
     ),

crates/apollo-compiler/test_data/err/0022_duplicate_interface_definitions.txt

@@ -21,7 +21,7 @@
                 ),
             },
             help: Some(
-                "NamedEntity must only be defined once in this document.",
+                "`NamedEntity` must only be defined once in this document.",
             ),
         },
     ),

crates/apollo-compiler/test_data/err/0029_directive_definitions_with_duplicate_names.txt

@@ -21,7 +21,7 @@
                 ),
             },
             help: Some(
-                "foo must only be defined once in this document.",
+                "`foo` must only be defined once in this document.",
             ),
         },
     ),

crates/apollo-compiler/test_data/err/0030_schema_with_duplicate_input_objects.txt

@@ -21,7 +21,7 @@
                 ),
             },
             help: Some(
-                "Point2D must only be defined once in this document.",
+                "`Point2D` must only be defined once in this document.",
             ),
         },
     ),