Send notification events when starting a call (#3248)

* Send notification events when starting a call

Previously this has been the responsibility of the hosting application (Element Web / Element X), but I would like to move this responsibility to Element Call itself to make it even more lightweight to integrate Element Call into a widget-capable client.

* use RTCNotification event

* add url param

* bump to latest js-sdk

* remove everything decline related

* use notification type in url params

* fix url .md docs

* back to `head=develop` and using js-sdk with send notification feature

* format

---------

Co-authored-by: Timo <toger5@hotmail.de>

yarn.lock

@@ -10247,7 +10247,7 @@ __metadata:
 
 "matrix-js-sdk@github:matrix-org/matrix-js-sdk#head=develop":
   version: 37.11.0
-  resolution: "matrix-js-sdk@https://github.com/matrix-org/matrix-js-sdk.git#commit=f8f1bf38373a944f12a739a301c1770c7bf08265"
+  resolution: "matrix-js-sdk@https://github.com/matrix-org/matrix-js-sdk.git#commit=aa79236ce23cef85583c802c0a9e8d1e77814d51"
   dependencies:
     "@babel/runtime": "npm:^7.12.5"
     "@matrix-org/matrix-sdk-crypto-wasm": "npm:^15.0.0"
@@ -10263,7 +10263,7 @@ __metadata:
     sdp-transform: "npm:^2.14.1"
     unhomoglyph: "npm:^1.0.6"
     uuid: "npm:11"
-  checksum: 10c0/e2090716731b04c52a6e23a6f06be59c39437c73f65b151d1c1d108c168f0fb1e3b6b23f229ddb0289cf3fb9cf304b4df63e84eae6ef198f29ee8d52f545c071
+  checksum: 10c0/33fb0918b0742c6a00ed0e4fd3cc958ae824d407f8e0e65687a011f8bbb058163e4123a7affce47368ca8489b96ccdceddfe98becc6a7c7aff7ab68b4e63a072
   languageName: node
   linkType: hard