Harvest 2.0 Original Metadata API route

[jbrown-xentity]

User Story

In order to have the originally harvested metadata, geospatial metadata users want an API that allows to get the original harvested metadata.

Acceptance Criteria

• [ ] GIVEN the harvester2.0 API is available and the route /harvest_record/raw/{id} is created
  WHEN a legitimate ID is used to hit the API at /harvest_record/raw/{id}
  THEN the original metadata is returned with correct formatting (ie xml, json, etc with correct content type)

Background

Related to https://github.com/GSA/data.gov/issues/4749, this ticket is required before #4749 can be taken on. Should consider updating the Flask Routes documentation

Security Considerations (required)

None

Sketch

Simply do the lookup in the DB for the information and return it. 404 if the resource is not in the DB. Make sure to setup the content type correctly for the different metadata standard, whether SML or JSON.