Element Call: fix widget shown while its still loading (waitForIframeLoad=false) (#12292)

* show loading spinner also if waitForIframeLoad = false
Configure EC so it waits for the content loaded action
!WARNING This breaks compatibility with the full mesh branch.
I would like to discuss here if/when we can do that.

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

* stop show loading screen on widget ready (instead of preparing)

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

* wait until widget loading is over before comparing screenshots

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

* fix waitForIFrame=true widgets

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

* test

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

* always start with loading true. + cleanup

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

* simplify loading

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

* update snapshots (start not in loading state for waitForIframe = true widgets)

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

---------

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

src/models/Call.ts

@@ -758,7 +758,7 @@ export class ElementCall extends Call {
                 name: "Element Call",
                 type: WidgetType.CALL.preferred,
                 url: url.toString(),
-                // waitForIframeLoad: false,
+                waitForIframeLoad: false,
                 data: ElementCall.getWidgetData(
                     client,
                     roomId,