Adds runbooks; the new API feature that makes it possible for
project members to self-serve maintenance tasks through curated step
lists associated with target nodes via traits.
In addition to basic CRUD support, runbook extends current API flow for
performing manual cleaning and servicing to support runbooks in lieu of
an explicit/arbitrary ``clean_steps`` and ``service_steps`` user-defined
lists.
Demo Video: https://youtu.be/00PJS4SXFYQ
Closes-Bug: #2027690
Change-Id: I43555ef72cb882adcada2ed875fda40eed0dd034