[MNG-6444] Internal code should prefer Path over File

**[Robert Scholte](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=rfscholte)** opened **[MNG-6444](https://issues.apache.org/jira/browse/MNG-6444?redirect=false)** and commented

Goal is to replace all '`new File(`' appearances with Path / Paths https://docs.oracle.com/javase/7/docs/api/java/nio/file/Path.html

---

**Issue Links:**
- [MNG-6071](https://issues.apache.org/jira/browse/MNG-6071) GetResource ('/) returns 'null' if build is started with -f

- [MNG-6437](https://issues.apache.org/jira/browse/MNG-6437) Generic .uri suffix to get the URI representation of any file property
(_**"is depended upon by"**_)