Add `media_google_cast` to Commanders Act media events

[defagos]

As a data analyst I would like to know when Google Cast is used so that I might find out how broadly this feature is used, when and how much.

Hints

• JIRA issue.
• API discussion.

Acceptance criteria

• Media events all contain a media_google_cast labels set to false on Apple platforms.

Tasks

• Add media_google_cast to parsed labels.
• Add media_google_cast to media events.