Fix endless ringing in ring-notification

[dremin]

Summary

When receiving multiple tasks, and they are both alerting at the same time, we would overwrite the mediaId of the first task, so we could not stop it when accepting. We avoid that scenario by returning in the play function if we are already playing.

As an initial attempt at the fix, I tried stopping the initial media when the second play was invoked, however, I found that in the case multiple reservations come to you at the same time, the stop would not actually prevent it playing when it was called before the audio file loaded. This may be an issue with the Flex AudioPlayerManager, but I did not look into this much further as the solution I landed upon seems to work well.

Checklist

• Tested changes end to end
• Requested one or more reviewers

[github-actions]

0 ESLint error(s) and 0 ESLint warning(s) found in pull request changed files.
✅ No issues found!

[trogers-twilio]

Nice catch. For future enhancement, we might want the ringing to begin again if there's still a reservation in pending after the current ringing one has triggered a stop. But not something to deal with in this PR.