As mentioned by @MusikAnimal on Slack:
what might be nice is to have a flag that controls rendering of new audio. Sure, that's the entire point of Phonos, but it could act like a kill switch in the event of widespread misuse. So if audio rendering is disabled, it simply shows the output without a link (unless the file already exists). That way, we don't have a situation where Phonos is in use on a lot of pages, and we want to roll it all back.
If we don't have this "kill switch", we'd have to disable the entire extension, which would make the raw <phonos> syntax visible everywhere it is in-use.
Acceptance criteria
- A configuration variable, $wgPhonosAudioGenerationEnabled, is set to true by default
- When $wgPhonosAudioGenerationEnabled is set to false, no new Phonos renders occur (i.e., no API requests/new files saved)
- Where a persisted file already exists, clicking the Phonos button will play the file
- Where a persisted file does not already exist, the Phonos button will display an error state (phonos-render-disabled)
