Adds missing API functions to PipelineC that will be needed by the
GraphQL API:
* Kinds enumeration
* Get Rank and parent of a Kind
* Enumerate and inspect Ranks
* Get a Step's parent
Included are some docstring fixes
This commit imports all the revng pipes (and other support utilities) to
be used with `revng-pipeline`. In particular, the pipes necessary for
binary translations have been introduced.