Push-to-talk via intents or physical button

### Your use case

It would be useful to assign a button to start recording voice message and send on release. Similar to zello functionality, this would allow walkie-talkie functionality with phones such as the Galaxy X Cover or Sonim XP8.

A quick way to add this functionality for developers to play with, would be to add intents that can press and depress the talk button. These can be utilized by applications outside element to trigger PTT. Tasker has automation to trigger intents for instance.

I think there is already a separate feature request for voice messages to automatically play, but that would be useful to bring walkie-talkie / Push-to-talk functionality together as well :)

### Have you considered any alternatives?

* Using Zello serves this purpose. It has remappable PTT button triggers and supports intents.

* Microsoft Teams has this feature as well.

### Additional context

Interested in bridging into other PTT/radio/RoIP systems for emergency services.

### Are you willing to provide a PR?

Yes