Rework both classes in schema_generator.py, main changes:
* Drop manager.pipeline_artifact_structure as it was used exclusively
by SchemaGenerator and is no longer needed
* Rename SchemaGen and BindableGen to SchemaGenerator and
DynamicBindableGenerator to better express their role, add
docstrings that explain what they do
* Decouple Artifacts and Analyses discovery, since a step can have
analyses and no artifacts (and vice-versa)
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.
Splits the module in 2:
* static_handlers: as the name suggests this is where handlers for
static endpoints (e.g. not dependent on the pipeline) are implemented
* schema_generator: this is where the schema is generated from a
manager's pipeline definition, together with the handler for the
autogenerated endpoint
Giacomo Vercesi