CS: forbid join alias function

Author: jrfnl

phpcs.xml.dist

@@ -135,6 +135,7 @@
                 <element key="print" value="echo"/>
                 <element key="is_null" value="null"/>
                 <element key="create_function" value="null"/>
+                <element key="join" value="implode"/>
             </property>
         </properties>
     </rule>