Add http live streaming (hls) support [Feature Request][UX]

[alltheseas]

User Story

As a Iris user who wants to engage in video streaming, I want Iris to render HTTP Live Streaming (HLS), so that I do not have to leave Iris messenger in order to experience a media stream.

Acceptance Criteria

1. Iris detects HLS (.m3u8) video format
2. Iris automagically plays HLS (.m3u8) format (if user selects this option in autoplay settings)
3. A setting is added in Iris settings that enables user to enable, or disable auto-play of HLS

https://developer.apple.com/streaming/examples/
https://developer.apple.com/streaming/examples/basic-stream-osx-ios5.html
Above link works in Safari browser.

Feature request created by @futurepaul on Damus github issues: damus-io/damus#798.