Share extension (#3506)

* Setup simple share extension

* Switch the app url scheme to be the full bundle identifier

* Setup a share extension that show a SwiftUI view, uses rust tracing and redirects to the hosting aplication

* Move media as json through the custom scheme into the main app and deep link into the media upload preview screen

* Fix message forwarding and global search screen room summary provider filtering.

* Tweak the message forwarding and global search screen designs.

* Add a room selection screen to use after receiving a share request from the share extension

* Fix share extension entitlements

* Share the temporary directory between the main app and the extensions; rename the caches one.

* Remove the no longer needed notification avatar flipping fix.

* Extract the placeholder avatar image generator from the NSE

* Nest `AvatarSize` within the new `Avatars` enum

* Donate an `INSendMessageIntent` to the system every time we send a message so they appear as share suggestions

* Support suggestions in the share extension itself

* Improve sharing animations and fix presentation when room already on the stack

* Clear all routes when sharing without a preselected room.

* Fix broken unit tests

* Various initial tweaks following code review.

* Correctly clean up and dismiss the share extension for all paths.

* Move the share extension path to a constants enum

* Rename UserSessionFlowCoordinator specific share extension states and events

* Add UserSession and Room flow coordinator share route tests

* Tweak the share extension logic.

ElementX/Sources/Application/AppCoordinator.swift

@@ -235,6 +235,12 @@ class AppCoordinator: AppCoordinatorProtocol, AuthenticationFlowCoordinatorDeleg
                 } else {
                     handleAppRoute(.childEventOnRoomAlias(eventID: eventID, alias: alias))
                 }
+            case .share:
+                guard isExternalURL else {
+                    MXLog.error("Received unexpected internal share route")
+                    break
+                }
+                handleAppRoute(route)
             default:
                 break
             }