Allow Element Call to be started without audio / video interface (#924)

* config: add feature in `config.json`

* groupCall: adjust connection state in feed if allowCallWithoutVideoAndAudio

* matrix-js-sdk: update version for allowCallWithoutVideoAndAudio

- I modified the SDK so that mute unmute work without media and check device permission inside the SDK
- allowCallWithoutVideoAndAudio is only checked at one point outside the SDK

* docu: add join group call without media docu in READMe

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Co-authored-by: Robin Townsend <robin@robin.town>
Co-authored-by: Šimon Brandner <simon.bra.ag@gmail.com>

package.json

@@ -46,7 +46,7 @@
     "i18next-browser-languagedetector": "^6.1.8",
     "i18next-http-backend": "^1.4.4",
     "lodash": "^4.17.21",
-    "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#64197bf4db6486d77708125d7fb2e8d7fe001f14",
+    "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#e782a2afa33032798eba7e92d2b3f28f9baa0564",
     "matrix-widget-api": "^1.0.0",
     "mermaid": "^8.13.8",
     "normalize.css": "^8.0.1",