(make-pipeline-a-solid-2) container_definition --> graph_definition

Summary:
Rename container_definition to graph_definition and make it required
in Solid.

Depends on D4847

Test Plan: BK

Reviewers: alangenfeld, max, dgibson, sandyryza

Reviewed By: sandyryza

Differential Revision: https://dagster.phacility.com/D4882