Add placeholders for relative packages paths

Currently, all paths are absolute (stored as Path object). There are cases where package path is needed e.g. in projects like CRISP where we have an external module (war):

target="{{projectRoot}}/example-commerce/src/main/java/org/onehippo/cms7/crisp/demo/example/commerce/model/Product.java"

This should be something like

target="{{projectRoot}}/example-commerce/src/main/java/{{projectPackageRelative}}/model/Product.java"

components, beans rest packages should be added as well..