Rewrite POM versions through Pom* views over the DomTrip model

[slachiewicz]

AbstractRewritePomsPhase.transformDocument walked the DomTrip model through the Maven 3 model classes and converted each list with toMavenCoordinates. It now works on small read-through views (PomModel, PomModelBase, PomBuild, PomBuildBase, PomPlugin, PomProfile), with the method names the Maven 4 port uses, so the port keeps this method and drops extends Model from the DomTrip classes instead. The four copies of the plugin and plugin-management loops become one rewriteBuildPlugins; the edit order is unchanged.

The DomTrip classes cannot implement the views directly while they extend the Maven 3 model (getDependencies() would need two return types), so ModelPomViews wraps the model. ModelETL.getPomModel() defaults to that view over getModel(), so any ModelETL implementation keeps working. The new types are @since 3.4, like the DomTrip classes.

Part of apache/maven#13309.

Verified: mvn verify → manager module 773 tests (4 new), 0 failures; the expected-POM rewrite tests pass unchanged.