Cache account management URL (#3826)

* cache account management URL

when sync starts

* better documentation

ElementX/Sources/Services/Client/ClientProxy.swift

@@ -280,6 +280,10 @@ class ClientProxy: ClientProxyProtocol {
         
         Task {
             await syncService?.start()
+            
+            // If we are using OIDC we want to cache the account management URL in volatile memory on the SDK side.
+            // To avoid the cache being invalidated while the app is backgrounded, we cache at every sync start.
+            await cacheAccountURL()
         }
     }
     
@@ -753,6 +757,11 @@ class ClientProxy: ClientProxyProtocol {
     
     // MARK: - Private
     
+    private func cacheAccountURL() async {
+        // Calling this function for the first time will cache the account URL in volatile memory for 24 hrs on the SDK.
+        _ = try? await client.accountUrl(action: nil)
+    }
+    
     private func updateVerificationState(_ verificationState: VerificationState) async {
         let verificationState: SessionVerificationState = switch verificationState {
         case .unknown:

ElementX/Sources/Services/Client/ClientProxyProtocol.swift

@@ -112,6 +112,7 @@ protocol ClientProxyProtocol: AnyObject, MediaLoaderProtocol {
     func startSync()
 
     func stopSync()
+    
     func stopSync(completion: (() -> Void)?) // Hopefully this will become async once we get SE-0371.
         
     func accountURL(action: AccountManagementAction) async -> URL?