Refactor CLI commands of network elements

The following discussion from !470 (merged) should be addressed:

• @hda11249 started a discussion: (+1 comment)

  The marked line is not relevant here. We should consider renaming this file and cmd to sth like deletePath. Only delete can lead to confusion.

Based on the linked discussion from above the CLI should be refactored to make it more clear that some of the commands access config paths of an network element. Therefore an additional sub-command path will be introduced.

The following call structure should be provided: networkelement path {set,get,delete}