[SQL][Function] Add replace() function (#4347)

replace is an user defined function, which is to replace all old substrings with a new substring in a string, as follow:
mysql> select replace("http://www.baidu.com:9090", "9090", "");
+------------------------------------------------------+
| replace('http://www.baidu.com:9090', '9090', '') |
+------------------------------------------------------+
| http://www.baidu.com: |
+------------------------------------------------------+

docs/en/sql-reference/sql-functions/string-functions/replace.md

@@ -0,0 +1,46 @@
+---
+{
+    "title": "replace",
+    "language": "zh-CN"
+}
+---
+
+<!--
+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.
+-->
+
+# replace
+## description
+### Syntax
+
+`VARCHAR REPLACE (VARCHAR str, VARCHAR old, VARCHAR new)`
+
+replace all old substring with new substring in str 
+
+## example
+
+```
+mysql> select replace("http://www.baidu.com:9090", "9090", "");
++------------------------------------------------------+
+| replace('http://www.baidu.com:9090', '9090', '') |
++------------------------------------------------------+
+| http://www.baidu.com:                                |
++------------------------------------------------------+
+```
+## keyword
+REPLACE