Add custom audio renderer for iPhone earpiece and only render joined participants (#3249)

* Add custom audio renderer to only render joined participants & add ios earpice workaround

fix left right to match chromium + safari
(firefox is swapped)

earpice as setting

Simpler code and documentation
The doc explains, what this class actually does and why it is so complicated.

Signed-off-by: Timo K <toger5@hotmail.de>

use only one audioContext, remove (non working) standby fallback

* Add tests

* use optional audio context and effect to initiate it + review

src/room/__snapshots__/InCallView.test.tsx.snap

@@ -9,7 +9,7 @@ exports[`InCallView > rendering > renders 1`] = `
       class="header filler"
     />
     <div>
-      mocked: RoomAudioRenderer
+      mocked: MatrixAudioRenderer
     </div>
     <div
       class="scrollingGrid grid"