fix empty state string in webxdc selector

deltachat-ios/Controller/WebxdcSelector.swift

@@ -44,7 +44,7 @@ class WebxdcSelector: UIViewController {
 
     private lazy var emptyStateView: EmptyStateLabel = {
         let label = EmptyStateLabel()
-        label.text = String.localized("tab_gallery_empty_hint")
+        label.text = String.localized("webxdc_empty_hint")
         label.isHidden = true
         return label
     }()

deltachat-ios/en.lproj/Localizable.strings

@@ -893,3 +893,4 @@
 "update_1_30" = "Faster. More stable.\n\nFor 1.30 releases, we focused on speed and reliability, fixing dozens of bugs. Check our changelogs if your favorite one is fixed: https://get.delta.chat/#changelogs 🚀";
 
 "webxdcs" = "Apps";
+"webxdc_empty_hint" = "Webxdc apps you have received or sent will appear here. You can tap on files to select downloaded apps.";