[HUDI-2362] Add external config file support (#3416)

Co-authored-by: Wenning Ding <wenningd@amazon.com>

hudi-common/src/test/resources/external-config/hudi-defaults.conf

@@ -0,0 +1,26 @@
+#
+# 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.
+#
+
+# Default system properties included when running Hudi jobs.
+# This is useful for setting default environmental settings.
+
+# Example:
+hoodie.datasource.hive_sync.jdbcurl            jdbc:hive2://localhost:10000
+hoodie.datasource.hive_sync.use_jdbc           true
+hoodie.datasource.hive_sync.support_timestamp  false
+hoodie.index.type                              BLOOM
+hoodie.metadata.enable                         true