* Let GraphQL accept zero or more parameters for analyses
* Handle the general case of analyses using zero or more containers with
a variable ammount of targets
This change fixes the pipeline behavior when producing targets:
* produce and extract now return rp_buffer, which has a start pointer
and size
* the python api `revng.api` will return on produce/extract either str
or bytes depending on the mime type of the container
* the GraphQL api will encode bytes in base64
When requesting a produce for multiple targets the result will be a
dictionary mapping "<target>:<result>". This also changes the GraphQL
API where a json-serialized string is returned.
This commit adds the newly implemented functionality in PipelineC both
in revng.api and the graphql api, allowing:
* retrieval of global variable names
* unwrapping of a single target
* execution of analyses
Giacomo Vercesi