Add description and command to pipeline dependency graph command nodes

[karkhaz]

Currently, the pipeline dependency graph is not as useful as it could be. The file nodes contain a truncated file name, and the command nodes contain a truncated description.

Acceptance:

• Use Graphviz HTML-like labels to create a two-section node for commands. The top section should contain the description (untruncated), and the bottom section should contain the full command line.