Align Application Descriptor Schema with latest structural updates

[dennis-behm]

The CBS in the ibm/dbb community repository have evolved via PR299 to reference external dependencies differently.

Migration Modeler needs to accommodate the new schema.

For dependencies:

dependencies: 
- name: ”retirementCalculator"
  type: "release"
  reference: "rel-1.2.0"
  buildid: "build-20241112.1"

And similarly for the baseline reference:

baselines:
- branch: "main"
  type: "release"
  reference: "rel-1.4.0"
  buildid: "20250224.4"