Assign a LearningResourceDepartment, LearningResourceDLC to resources when appropriate

User Story

As a podcast listener, I would like to know which MIT Department (or DLC - Lab/Center/Institute), if any, produces each podcast.
Ditto for other learning resources where applicable.

Description/Context

• Create a new LearningResourceDLC class with fields like name and maybe dlc_id, url - similar to LearningResourceDepartment. Add to LearningResource class as a nullable field (dlc?) via foreign key.
• Assign department and/or DLC (if any) as part of the ETL process - extract from the catalog API response if present.

Acceptance Criteria

• The yaml files for podcasts have fields for offered_by, department, and dlc where applicable
• LearningResources will have a non-null department and DLC where applicable

Plan/Design

• Create a new LearningResourceDLC class with fields like name and maybe dlc_id, url - similar to LearningResourceDepartment. Add to LearningResource class as a nullable field (dlc?) via foreign key.
• Assign department and/or DLC where applicable as part of the ETL process - extract from the catalog API response if present.
• Update the podcast yaml files to include fields for offered_by, department, and dlc where applicable
• Out of scope (issue per app): update each online app's catalog API response to include these field where applicable, otherwise they will be assumed to be null.

Start by locating LearningResourceDepartment, LearningResource, and the ETL pipeline, then inspect the catalog API response fields available for departments and DLCs. Review the podcast YAML files and determine how offered_by, department, and dlc should be represented. Done means applicable resources have department and DLC data, and the acceptance criteria are met without changing the online apps.