Add support for sharing URLs and text. (#3546)

* Add support for sharing URLs and text.

* Fix a bug where a stored draft would overwrite the shared text.

* Add tests.

ElementX/Sources/Screens/RoomScreen/RoomScreenCoordinator.swift

@@ -15,6 +15,7 @@ struct RoomScreenCoordinatorParameters {
     let clientProxy: ClientProxyProtocol
     let roomProxy: JoinedRoomProxyProtocol
     var focussedEvent: FocusEvent?
+    var sharedText: String?
     let timelineController: RoomTimelineControllerProtocol
     let mediaProvider: MediaProviderProtocol
     let mediaPlayerProvider: MediaPlayerProviderProtocol
@@ -88,7 +89,8 @@ final class RoomScreenCoordinator: CoordinatorProtocol {
                                                     maxCompressedHeight: ComposerConstant.maxHeight,
                                                     maxExpandedHeight: ComposerConstant.maxHeight,
                                                     parserStyle: .elementX)
-        let composerViewModel = ComposerToolbarViewModel(wysiwygViewModel: wysiwygViewModel,
+        let composerViewModel = ComposerToolbarViewModel(initialText: parameters.sharedText,
+                                                         wysiwygViewModel: wysiwygViewModel,
                                                          completionSuggestionService: parameters.completionSuggestionService,
                                                          mediaProvider: parameters.mediaProvider,
                                                          mentionDisplayHelper: ComposerMentionDisplayHelper(timelineContext: timelineViewModel.context),
@@ -172,7 +174,7 @@ final class RoomScreenCoordinator: CoordinatorProtocol {
             .store(in: &cancellables)
         
         // Loading the draft requires the subscriptions to be set up first otherwise the room won't be be able to propagate the information to the composer.
-        composerViewModel.loadDraft()
+        Task { await composerViewModel.loadDraft() }
     }
     
     func focusOnEvent(_ focussedEvent: FocusEvent) {
@@ -183,6 +185,12 @@ final class RoomScreenCoordinator: CoordinatorProtocol {
         Task { await timelineViewModel.focusOnEvent(eventID: eventID) }
     }
     
+    func shareText(_ string: String) {
+        composerViewModel.process(timelineAction: .setMode(mode: .default)) // Make sure we're not e.g. replying.
+        composerViewModel.process(timelineAction: .setText(plainText: string, htmlText: nil))
+        composerViewModel.process(timelineAction: .setFocus)
+    }
+    
     func stop() {
         composerViewModel.saveDraft()
         timelineViewModel.stop()