Render a player fallback for `m.audio` messages

#### Is your feature request related to a problem? Please describe.
Currently most clients, that aren't Element, use `m.audio` to send voice messages. In the future the spec will only support voice messages for sending voice messages, but until other clients can catch up and to prevent small client devs from being flooded with bug reports, because users can't listen to voice messages from some clients, it would be nice to offer at least some compatibility for some time. Currently Element Android renders them as files, which makes a user assume, the other client sent a broken event. FluffyChat has been using `m.audio` for more than a year to send voice messages, which is used a lot in schools and other areas, where people have trouble typing. It would be nice Element Android could render at least a basic play button, like is done for voice messages, for audio events until other clients had time to transition to a stable spec to reduce friction for client devs and users.

#### Describe the solution you'd like.
Support some way of playing audio events in addition to voice messages. This would probably also be nice UX wise to listen in on normal audio messages.

#### Describe alternatives you've considered.
Nothing that is reasonable to request.

#### Additional context
https://matrix.to/#/%23fluffychat%3Amatrix.org/%24LLIzmd-AGinAYPOo1IoCw-zAXtr6CwO00mfwll53Niw?via=neko.dev&via=matrix.org&via=the-apothecary.club&via=20kdc.duckdns.org