TF-2384 Handle NSE to get plain notification in iOS

Signed-off-by: dab246 <tdvu@linagora.com>
(cherry picked from commit 364f32a14b9888f73a3a103b8b5e1bc9b31e148e)

ios/TwakeMailNSE/Model/KeychainSharingSession.swift

@@ -0,0 +1,39 @@
+import Foundation
+
+struct KeychainSharingSession: Codable {
+    let accountId: String
+    let userName: String
+    let authenticationType: AuthenticationType
+    let apiUrl: String
+    let emailState: String?
+    let tokenOIDC: TokenOidc?
+    let basicAuth: String?
+}
+
+extension KeychainSharingSession {
+    func updateEmailState(newState: String) -> KeychainSharingSession {
+        return KeychainSharingSession(
+            accountId: self.accountId,
+            userName: self.userName,
+            authenticationType: self.authenticationType,
+            apiUrl: self.apiUrl,
+            emailState: newState,
+            tokenOIDC: self.tokenOIDC,
+            basicAuth: self.basicAuth
+        )
+    }
+    
+    func toData() -> Data? {
+        if let encodedData = try? JSONEncoder().encode(self) {
+            return encodedData
+        }
+        return nil
+    }
+    
+    func toJson() -> String? {
+        if let data = toData(), let jsonString = String(data: data, encoding: .utf8) {
+            return jsonString
+        }
+        return nil
+    }
+}