Fix empty filename not checked (#3693)

* Add localizable

Signed-off-by: Milen Pivchev <milen.pivchev@gmail.com>

* Trim whitespaces

Signed-off-by: Milen Pivchev <milen.pivchev@gmail.com>

---------

Signed-off-by: Milen Pivchev <milen.pivchev@gmail.com>

Author: mpivchev

iOSClient/Extensions/UIAlertController+Extension.swift

@@ -216,7 +216,7 @@ extension UIAlertController {
 
         let oldExtension = fileName.fileExtension
 
-        let text = alertController.textFields?.first?.text ?? ""
+        let text = alertController.textFields?.first?.text?.trimmingCharacters(in: .whitespaces) ?? ""
         let textCheck = FileNameValidator.checkFileName(text, account: account, capabilities: capabilities)
         var message = textCheck?.error.localizedDescription ?? ""
         var messageColor = UIColor.red

iOSClient/Supporting Files/en.lproj/Localizable.strings

@@ -703,6 +703,7 @@ You can stop it at any time, adjust the settings, and enable it again.";
 "_file_name_validator_error_invalid_character_" = "Name contains an invalid character: \"%@\".";
 "_file_name_validator_error_space_" = "Name must not contain spaces at the beginning or end.";
 "_file_name_new_extension_" = "Changing the extension might cause this file to open in a different application.";
+"_file_name_empty_" = "File name cannot be empty.";
 "_please_rename_file_" = "Please rename the file or folder.";
 "hidden_file_name_warning" = "Name will result in a hidden file.";