AvatarView: Update AvatarViewDataProtocol, add possibility to set a defaut image.

Riot/Modules/Common/Avatar/AvatarViewDataProtocol.swift

@@ -14,19 +14,28 @@
 // limitations under the License.
 //
 
-import Foundation
+import UIKit
+
+enum AvatarFallbackImage {
+    
+    /// matrixItem represent a Matrix item like a room, space, user
+    /// matrixItemId: Matrix item identifier (user id or room id)
+    /// displayName: Matrix item display name (user or room display name)
+    case matrixItem(_ matrixItemId: String, _ displayName: String?)
+    
+    /// Normal image with optional content mode
+    case image(_ image: UIImage, _ contentMode: UIView.ContentMode? = nil)
+}
 
 /// AvatarViewDataProtocol describe a view data that should be given to an AvatarView sublcass
 protocol AvatarViewDataProtocol {
-    /// Matrix item identifier (user id or room id)
-    var matrixItemId: String { get }
-    
-    /// Matrix item display name (user or room display name)
-    var displayName: String? { get }
     
     /// Matrix item avatar URL (user or room avatar url)
-    var avatarUrl: String? { get }
+    var avatarUrl: String? { get }            
         
     /// Matrix media handler
     var mediaManager: MXMediaManager { get }
+    
+    /// Fallback image used when avatarUrl is nil
+    var fallbackImage: AvatarFallbackImage? { get }
 }