Use a custom copyright license matcher for RAT to allow usage of https links in copyright headers

A recent commit changed the license text in the copyright header on source
files to use https instead of http for refering to the license file. This
causes RAT tool to not match such copyright headers against
Apache License, Version 2.0. The use of "https" instead of "http" in the
copyright headers is considered valid as per the discussion here
https://mail-archives.apache.org/mod_mbox/ant-dev/201905.mbox/%3C87ftowunkc.fsf%40v45346.1blu.de%3E

This commit introduces a custom license matcher for RAT which matches
such copyright headers and considers them as "approved".

check.xml

@@ -105,7 +105,7 @@
 
   <!-- Apache Rat: Release Auditing Tool -->
   <property name="rat.version"
-            value="0.12"
+            value="0.13"
             description="Which version of Apache Rat to use"/>
   <property name="rat.report.dir"
             value="${reports.dir}/rat"
@@ -311,6 +311,25 @@
              classpathref="rat.classpath"/>
     <mkdir dir="${rat.report.dir}"/>
     <rat:report xmlns:rat="antlib:org.apache.rat.anttasks" reportfile="${rat.report.dir}/report.txt">
+      <rat:fullTextMatcher licenseFamilyCategory="AL   "
+             licenseFamilyName="Apache License Version 2.0 with HTTPS reference">
+Licensed to the Apache Software Foundation (ASF) under one or more
+contributor license agreements.  See the NOTICE file distributed with
+this work for additional information regarding copyright ownership.
+The ASF licenses this file to You under the Apache License, Version 2.0
+(the "License"); you may not use this file except in compliance with
+the License.  You may obtain a copy of the License at
+
+   https://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+      </rat:fullTextMatcher>
+      <rat:approvedLicense
+             familyName="Apache License Version 2.0 with HTTPS reference"/>
       <fileset dir="${java.dir}">
         <exclude name="org/apache/tools/ant/defaultManifest.mf"/>
         <exclude name="org/apache/tools/ant/version.txt"/>