Inject entity manager and field type manager to Entity destinations

Problem/Motivation

#2590993: Create stub entities with proper default values introduces use of \Drupal::entityManager() and \Drupal::service('plugin.manager.field.field_type') to Entity-based destinations. These would be better injected.

Proposed resolution

Inject all the things!

Remaining tasks

Add injection to the Entity destination plugin and its derived classes.

User interface changes

N/A

API changes

None

Data model changes

None