Move ConflictingNamesTest to lib/go/test

Client: go

Also add missing copyright header for files added in
https://github.com/apache/thrift/pull/2307.
diff --git a/lib/go/test/ConflictArgNamesTest.thrift b/lib/go/test/ConflictArgNamesTest.thrift
new file mode 100644
index 0000000..11323ec
--- /dev/null
+++ b/lib/go/test/ConflictArgNamesTest.thrift
@@ -0,0 +1,32 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+service ConflictArgNamesTest {
+  /**
+   * Use some names that could conflict with the compiler code as args
+   * to make sure that the compiler handled them correctly.
+   */
+  void testNameConflicts(
+    // 1: string args, // args is already a reserved keyword in thrift compiler
+    2: string result,
+    3: string meta,
+    4: string r,
+    5: string err,
+  )
+}