* Integrate Element Call with widget API.
- Add `appconfig` module and extract constants that can be overridden in forks there.
- Add an Element Call feature flag, disabled by default.
- Refactor the whole `ElementCallActivity`, move most logic out of it.
- Integrate with the Rust Widget Driver API (note the Rust SDK version used in this PR lacks some needed changes to make the calls actually work).
- Handle calls differently based on `CallType`.
- Add UI to create/join a call.
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Co-authored-by: ElementBot <benoitm+elementbot@element.io>
* Notifications: Add some extra mappings so we keep the original contents and can pass it later to an UI layer
* Fix notifications not appearing for a room if the app was on that room when it went to background.
* Modernize how we create spannable strings for notifications, remove unneeded dependency
* Remove actions from invite notifications temporarily
* Add `NotificationDrawerManager` interface to be able to clear membership notifications when accepting or rejecting a room invite
* Fix tests
* Add comment to clarify some weird behaviours
* Address review comments
* Set circle shape for `largeBitmap` in message notifications
* Fix no avatar in DM rooms
* Fix rebase issues
* Add invite list pending intent:
- Refactor pending intents.
- Make `DeepLinkData` a sealed interface.
- Fix and add tests.
* Rename `navigate__` functions to `attach__`
* Add an extra test case for the `InviteList` deep link
* Address most review comments.
* Fix rebase issue
* Add fallback notification type, allow dismissing invite notifications.
Fallback notifications have a different underlying type and can be dismissed at will.
* Fix tests