Timeline item sender profiles (#463)

* Adopt timeline item sender profiles for displaying user avatars and display names
* Prevent images from automatically being evicted from the in-memory cache when entering background
* Get rid of all the `urlString: String`s and start using proper URLs
* Add back manual display name loading as the sender profiles aren't working properly yet
* Implement a sender profile.
* Bump the RustSDK to v1.0.32-alpha

Co-authored-by: Doug <douglase@element.io>

ElementX/Sources/Services/Timeline/TimelineItemSender.swift

@@ -0,0 +1,27 @@
+//
+// Copyright 2023 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import UIKit
+
+#warning("This could be replaced by RoomMemberProxy if Rust includes a RoomMember.")
+struct TimelineItemSender: Identifiable, Hashable {
+    let id: String
+    
+    // Lazy loaded properties, displayName and avatarURL will be come lets.
+    var displayName: String?
+    var avatarURL: URL?
+    var avatar: UIImage?
+}