feat(contentHint): emit event on contentHint change

[lismith2-cisco]

Description

not sure about having video-only event, it causes type issues in wcme

This change implements...

• A new feature
• A bug fix
• Other (please specify):

Is this a breaking change?

• Yes
• No

I certify that...

• All relevant unit and integration tests have passed and/or have been updated according to this change.

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