Migrate off jdom2 and use the DOM parser/builder built into the JDK instead

### New feature, improvement proposal

Currently archetype-common uses `jdom2` in the `MavenJDOMWriter` and associated utility classes, AFAICT mainly write a pom in `DefaultPomManager.writePom()`.

In order to reduce the dependency footprint, would it be possible to migrate off jdom2 and use the DOM-parser/builder built into the JDK instead? Or are there particular reasons to use jdom(2) instead?

If you consider `MavenJDOMWriter` or the associated utility classes as part of the API, for now, it could just be deprecated and a colocated `MavenDOMWriter` could be added, which is used by archetype and the dependency to jdom2 could be made optional.

Start with MavenJDOMWriter and its associated utility classes, then trace how DefaultPomManager.writePom() uses them to write a POM. Compare the requested JDK DOM parser/builder replacement with the current jdom2 usage, including whether the existing classes are part of the API. Done means the migration approach is defined, with compatibility or deprecation and dependency-optional behavior addressed where needed.

Written by the indexing model from the issue text.