Enhance CBS scripts to fetch external dependencies

[dennis-behm]

This is extending the existing common backend scripts dbbBuild.sh and zBuilder.sh to automatically fetch external dependencies from an artifact repository (instead of any concatenation).

High-level capabilities:

• Read build dependency configuration defined in the Application Descriptor.
• Load external dependencies based on naming conventions of the CBS from an artifact repository (Nexus, Artifactory)
• Expand the external dependencies in the build workspace for consumption by the build framework