Add support for entity_reference_media fields

Problem/Motivation

Currently, entity_reference_media fields from the corresponding module → are not used for tracking the usages of media entities.

Steps to reproduce

• Add a field of type entity_reference_media to a node type
• Add media content to that field
• Check usages for the media: 0

Proposed resolution

Add entity_reference_media to the field_types of Drupal\entity_usage\Plugin\EntityUsage\Track\EntityReference

Remaining tasks

User interface changes

API changes

Data model changes