feat: add accessibleDisabledButtons feature flag (#20845)

* feat: add feature flag for focusable disabled components

* rename feature flag

Author: vursen

flow-server/src/main/java/com/vaadin/experimental/FeatureFlags.java

@@ -99,6 +99,10 @@ public class FeatureFlags implements Serializable {
             "React 19 (default in Vaadin 25)", "react19",
             "https://react.dev/blog/2024/12/05/react-19", true, null);
 
+    public static final Feature ACCESSIBLE_DISABLED_BUTTONS = new Feature(
+            "Accessible disabled buttons", "accessibleDisabledButtons",
+            "https://github.com/vaadin/web-components/issues/4585", true, null);
+
     private List<Feature> features = new ArrayList<>();
 
     File propertiesFolder = null;
@@ -128,6 +132,7 @@ public FeatureFlags(Lookup lookup) {
         features.add(new Feature(DASHBOARD_COMPONENT));
         features.add(new Feature(CARD_COMPONENT));
         features.add(new Feature(REACT19));
+        features.add(new Feature(ACCESSIBLE_DISABLED_BUTTONS));
         loadProperties();
     }