Fix S2068 TP/FP: Stop raising issues for form credentials of web.config

[hendrik-buchwald-sonarsource]

Description

In SONARXML-169 support for hardcoded clear-text credentials in web.config files was added. Now there is an overlap with the rule for sonar-dotnet, i.e. issues will be reported twice. So even though it is a true positive, it would be best if sonar-dotnet does not raise an issue for this specific case anymore.

There is also a false positive that is raised for the attribute passwordFormat that sets the password format.

Repro steps

<configuration>
  <system.web>
     <authentication mode="Forms">
      <forms>
        <credentials passwordFormat="Clear">  <!-- FP -->
          <user name="admin" password="password" />  <!-- unwanted TP -->
        </credentials>
      </forms>
    </authentication>
  </system.web>
</configuration>

Expected behavior

No issues should be raised in web.config files for children of <configuration><system.web><authentication mode="Forms"><forms> that contain attributes with a keyword like password.

Actual behavior

Issues are raised for <credentials passwordFormat="Clear"> and <user name="admin" password="password" />.