MatchXpath: should support comments

[rnveach]

Similar to #7531

$ cat TestClass.java
public class TestClass {
    void method() {
// test
    }
}

$ cat TestConfig.xml
<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
          "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
          "https://checkstyle.org/dtds/configuration_1_3.dtd">

<module name="Checker">
    <property name="charset" value="UTF-8"/>

    <module name="TreeWalker">
<module name="MatchXpath">
  <property name="query" value="//SINGLE_LINE_COMMENT" />
</module>
    </module>
</module>

$ java -jar checkstyle-8.43-all.jar -c TestConfig.xml TestClass.java
Starting audit...
Audit done.

MatchXpath can't flag comments because it is not a comment aware check.

I don't believe it is at all related to PR #9832 since xpath relies on the tokens given to it and checks that aren't comment aware won't receive comments.

[AkMo3]

I am on it !

[strkkk]

Just a note - this change can break backwards compatibility.

[romani]

fix is merged.
@AkMo3 , thanks a lot for your help.