WSTEAM1-733 Display audio on the Live Page

[emilysaffron]

Resolves JIRA WSTEAM1-733 Overall changes

Displays audio within live page posts

Code changes

• adds audio rendered with the MediaLoader to componentsToRender within Post
• adds fixture data and unit test

Testing

1. Visit http://localhost.bbc.com:7081/mundo/live/cemn2qq3x8vt?renderer_env=test and find the post with embedded audio. Observe the working audio player, make sure it looks correct and functions. (Media playing twice is a react re-rendering issue and is expected, it works fine not on local)

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