Warn and block sending on verification violation (#3679)

* feat(crypto): Warn and block sending on verification violation

* fixup: Fix ComposerToolbar previews

* fixup! add ComposerToolBarViewModelTests for canSend

* add new preview tests for verification violations

* Use `deferFulfillment`s in the unit tests.

---------

Co-authored-by: Stefan Ceriu <stefanc@matrix.org>

ElementX/Sources/Screens/RoomScreen/ComposerToolbar/ComposerToolbarModels.swift

@@ -66,6 +66,8 @@ enum ComposerAttachmentType {
 struct ComposerToolbarViewState: BindableState {
     var composerMode: ComposerMode = .default
     var composerEmpty = true
+    /// Could be false if sending is disabled in the room
+    var canSend = true
     var suggestions: [SuggestionItem] = []
     var audioPlayerState: AudioPlayerState
     var audioRecorderState: AudioRecorderState
@@ -97,6 +99,10 @@ struct ComposerToolbarViewState: BindableState {
     }
     
     var sendButtonDisabled: Bool {
+        if !canSend {
+            return true
+        }
+        
         if case .previewVoiceMessage = composerMode {
             return false
         }