Provide a inline form handler to ensure ->save(TRUE) is called

Problem/Motivation

When a user uploads a brightcove video, it should be uploaded to brightcove. When you use inline_entity_form to embed a brightcove video inside a media entity for example
though, \Drupal\brightcove\Form\BrightcoveVideoForm::save is not called. This is by design of IEF

Proposed resolution

Provide a inline form implementation which calls ::save(TRUE)

Remaining tasks

User interface changes

API changes

Data model changes