Improved target names variables

[ademariag]

When using the compose_node_name: true, for example for the following

gcp\
  project1.yml
  project2.yml

then the inventory will render as such:

parameters:
  _reclass_:
    environment: base
    name:
      full: gcp.project1
      short: gcp

while the expected behaviour for Kapitan would be

parameters:
  _reclass_:
    environment: base
    name:
      full: gcp.project1
      short: project1

Additionally, this PR also adds support for exposing the list of parts composing the path

parameters:
  _reclass_:
    environment: base
    name:
      full: gcp.project1
      parts:
        - gcp
        - project1
      path: gcp/project1
      short: project1

[uberspot]

Nice!