[MCHECKSTYLE-431] Avoid creating unnecessary target files for pom projects

**[Alexis Jehan](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=alexisj)** opened **[MCHECKSTYLE-431](https://issues.apache.org/jira/browse/MCHECKSTYLE-431?redirect=false)** and commented

Because pom projects do not have Java code, It is not necessary to create "target/checkstyle-cachefile", "target/checkstyle-checker.xml", "target/checkstyle-result.xml" and "target/checkstyle-suppressions.xml" files for these projects.

Maven configuration:

```xml

org.apache.maven.plugins
maven-checkstyle-plugin
3.2.1


com.puppycrawl.tools
checkstyle
10.9.3



checkstyle.xml
checkstyle-suppressions.xml
true
info



checkstyle-check
validate

check

```

Maven output:

```
[INFO] --- checkstyle:3.2.1:check (checkstyle-check) @ parent-project ---
[INFO] You have 0 Checkstyle violations.
```

Content of the generated "target/checkstyle-result.xml":

```xml

```

---

**Affects:** 3.2.1

Start by reproducing the Maven configuration and output for a pom project, then trace where target/checkstyle-cachefile, target/checkstyle-checker.xml, target/checkstyle-result.xml, and target/checkstyle-suppressions.xml are generated. Done means a pom project without Java code no longer creates these files while the check goal still runs successfully.

Written by the indexing model from the issue text.