[dagit] Give Sensors and Schedules unique IDs
Summary: Current IDs for Schedules and Sensors are not properly unique across repos, since they just glue together the schedule/sensor name and the pipeline name, both of which can be repeated in separate repos. This causes problems for Apollo caching.
Test Plan: Buildkite. Run Dagit, inspect Apollo cache, verify presence of new IDs.
Reviewers: yuhan, alangenfeld, dgibson
Reviewed By: alangenfeld
Differential Revision: https://dagster.phacility.com/D8644