Media loading flow changes (#483)

* Use an imageProvider directly from the view in the home screen

* Add support for media request coalescing

* Rename MediaProxy to MediaLoader

* Add new image loading mechanism to the room details screen avatar.

* Use the `SettingsScreen` prefix for all settings screen related components

* Add new image loading mechanism to the room header

* Add new image loading mechanism to the room member details screen

* Introduce a LoadableImage SwiftUI view that will automatically handle image loading

* Adopt the new LoadableImage where possible

* Fix LoadableImage not using/storing loaded images properly

* Simplify media loader enqueueing

* Made LodableImage load content after mediaSource updates. Adopt it on the home and settings screens

* Introduce a LoadableAvatarImage component and reuse it throughout the app

* Small logging tweaks, made some LoadableImage properties private

* Fix redacted skeletons avatar background color

* Fix placeholder avatars changing when backgrounding the app

* PR comments.

- Trim the @ sign off of mxid placeholders.
- Only expose AvatarSize on the avatar image, use CGSize elsewhere.

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

UnitTests/Sources/MediaProvider/MediaLoaderTests.swift

@@ -0,0 +1,115 @@
+//
+// 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.
+//
+
+@testable import ElementX
+import MatrixRustSDK
+import XCTest
+
+final class MediaLoaderTests: XCTestCase {
+    func testMediaRequestCoalescing() async {
+        let mediaLoadingClient = MockMediaLoadingClient()
+        let mediaLoader = MediaLoader(client: mediaLoadingClient)
+        
+        let mediaSource = MediaSourceProxy(url: URL.documentsDirectory)
+        
+        do {
+            for _ in 1...10 {
+                _ = try await mediaLoader.loadMediaContentForSource(mediaSource)
+            }
+            
+            XCTAssertEqual(mediaLoadingClient.numberOfInvocations, 10)
+        } catch {
+            fatalError()
+        }
+    }
+    
+    func testMediaThumbnailRequestCoalescing() async {
+        let mediaLoadingClient = MockMediaLoadingClient()
+        let mediaLoader = MediaLoader(client: mediaLoadingClient)
+        
+        let mediaSource = MediaSourceProxy(url: URL.documentsDirectory)
+        
+        do {
+            for _ in 1...10 {
+                _ = try await mediaLoader.loadMediaThumbnailForSource(mediaSource, width: 100, height: 100)
+            }
+            
+            XCTAssertEqual(mediaLoadingClient.numberOfInvocations, 10)
+        } catch {
+            fatalError()
+        }
+    }
+}
+
+private class MockMediaLoadingClient: ClientProtocol {
+    private(set) var numberOfInvocations = 0
+    
+    func getMediaContent(source: MatrixRustSDK.MediaSource) throws -> [UInt8] {
+        numberOfInvocations += 1
+        return []
+    }
+    
+    func getMediaThumbnail(source: MatrixRustSDK.MediaSource, width: UInt64, height: UInt64) throws -> [UInt8] {
+        numberOfInvocations += 1
+        return []
+    }
+    
+    // MARK: - Not implemented
+    
+    func setDelegate(delegate: MatrixRustSDK.ClientDelegate?) { }
+    
+    func login(username: String, password: String, initialDeviceName: String?, deviceId: String?) throws { }
+    
+    func restoreSession(session: MatrixRustSDK.Session) throws { }
+    
+    func session() throws -> MatrixRustSDK.Session { fatalError() }
+    
+    func userId() throws -> String { fatalError() }
+    
+    func displayName() throws -> String { fatalError() }
+    
+    func setDisplayName(name: String) throws { }
+    
+    func avatarUrl() throws -> String { fatalError() }
+    
+    func deviceId() throws -> String { fatalError() }
+    
+    func accountData(eventType: String) throws -> String? { fatalError() }
+    
+    func setAccountData(eventType: String, content: String) throws { fatalError() }
+    
+    func uploadMedia(mimeType: String, content: [UInt8]) throws -> String { fatalError() }
+    
+    func getSessionVerificationController() throws -> MatrixRustSDK.SessionVerificationController { fatalError() }
+    
+    func fullSlidingSync() throws -> MatrixRustSDK.SlidingSync { fatalError() }
+    
+    func logout() throws { }
+    
+    func hasFirstSynced() -> Bool { fatalError() }
+    
+    func homeserver() -> String { fatalError() }
+    
+    func isSoftLogout() -> Bool { fatalError() }
+    
+    func isSyncing() -> Bool { fatalError() }
+    
+    func rooms() -> [MatrixRustSDK.Room] { fatalError() }
+    
+    func slidingSync() -> MatrixRustSDK.SlidingSyncBuilder { fatalError() }
+    
+    func startSync(timelineLimit: UInt16?) { }
+}