Use Safari for OIDC account URL. (#1591)

* Handle RP-Initiated Logout URL.

Safari is only used on devices, the simulator doesn't work properly.

ElementX/Sources/Services/Client/ClientProxy.swift

@@ -306,13 +306,13 @@ class ClientProxy: ClientProxyProtocol {
         }
     }
 
-    func logout() async {
+    func logout() async -> URL? {
         await Task.dispatch(on: clientQueue) {
             do {
-                // We aren't currently handling the RP initiated sign out URL.
-                _ = try self.client.logout()
+                return try self.client.logout().flatMap(URL.init(string:))
             } catch {
                 MXLog.error("Failed logging out with error: \(error)")
+                return nil
             }
         }
     }

ElementX/Sources/Services/Client/ClientProxyProtocol.swift

@@ -107,7 +107,7 @@ protocol ClientProxyProtocol: AnyObject, MediaLoaderProtocol {
     
     func sessionVerificationControllerProxy() async -> Result<SessionVerificationControllerProxyProtocol, ClientProxyError>
 
-    func logout() async
+    func logout() async -> URL?
 
     func setPusher(with configuration: PusherConfiguration) async throws
     

ElementX/Sources/Services/Client/MockClientProxy.swift

@@ -116,8 +116,8 @@ class MockClientProxy: ClientProxyProtocol {
         }
     }
     
-    func logout() async {
-        // no-op
+    func logout() async -> URL? {
+        nil
     }
     
     var setPusherErrorToThrow: Error?