Allows overriding or augmenting the default values set by the Jitsi Meet web app using the config parameter.

Many of the events are not used at all or used only on one place. For the rest of them the listeners were added 2 times on promoted visitors and not cleaned at all.

* fix: Drop duplicate call of wait for owner.

* fix: Fixes leaking listeners while waiting for host to join.

While waiting for the host to join on the dialog we attempt to join over and over again till we are admitted to enter the meeting. While doing that authRequired flag is on, and we were adding listeners on and on.

* feat: Introduces conference join in progress action.

This event is coming from lib-jitsi-meet and is fired when we receive the first presence of series when joining. It is always fired before joined event.

* fix: Moves testing middleware to use CONFERENCE_JOIN_IN_PROGRESS.

* fix: Moves follow-me middleware to use CONFERENCE_JOIN_IN_PROGRESS.

* fix: Moves some polls logic to middleware and use CONFERENCE_JOIN_IN_PROGRESS.

* fix: Moves reactions middleware to use CONFERENCE_JOIN_IN_PROGRESS.

* fix: Moves recordings middleware to use CONFERENCE_JOIN_IN_PROGRESS.

* fix: Moves shared-video middleware to use CONFERENCE_JOIN_IN_PROGRESS.

* fix: Moves videosipgw middleware to use CONFERENCE_JOIN_IN_PROGRESS.

* squash: Fix comments.

* fix: Fixes join in progress on web.

* fix: Moves variable extraction inside handlers.

* fix: Moves variable extraction inside handlers again.

* fix: Moves etherpad middleware to use CONFERENCE_JOIN_IN_PROGRESS.