Sensor invocation, remove evaluate_tick from API docs, change testing story
This diff changes away from using evaluate_tick for testing sensors, and instead supports direct sensor invocation for sensors created via a decorator.
I left decorated_fn optional for backcompat with people who defined sensors using constructor. How do we want to support SensorDefinitions created from constructor? Should we default to evaluation_fn if decorated_fn is not provided?
Unit tests + docs build
Reviewers: sandyryza, alangenfeld, prha
Reviewed By: alangenfeld
Differential Revision: https://dagster.phacility.com/D8239