fix weird focus issues with android OSK

lib/helpers/extensions/refocus_after_rebuild.dart

@@ -0,0 +1,9 @@
+import "package:material_ui/material_ui.dart";
+
+extension RefocusAfterRebuild on FocusNode {
+  /// Focuses this again once the text field using it has been replaced.
+  void refocusAfterRebuild() {
+    unfocus();
+    WidgetsBinding.instance.addPostFrameCallback((_) => requestFocus());
+  }
+}