Remove legacy signaling and legacy SS mode. (#12499)
* fix(connection-status): remove unused participant connectionStatus.
Always use trackStreamingStatus now that legacy endpoint based signaling has been removed.
* remove the check for source-name signaling.
Default to source-name signaling always.
* Remove the check for multi-stream mode.
Make that the default mode and remove the support for legacy SS mode.
* Remove presenter mode.
* update latest@lib-jitsi-meet
feat(toolbar-button-clicked) Enhance toolbar buttons with notify click
- add possibility to allow execution of the button's routine besides triggering
`toolbarButtonClicked` API event
- keep backwards compatibility
- get rid of `ToolbarButton`
audio-only,lastn: move audio-only and last N handling to standalone features
This refactors all handling of audio-only and last N to 2 features in preparation
for "low bandwidth mode".
The main motivation to do this is that lastN is a "global" setting so it helps
to have all processing for it in a single place.
Contributing all buttons in one place goes against the designs that we
set out at the beginning of the project's rewrite and that multiple of
us have been following since then.