[API] Add support for DockBuilder

imgui-binding/src/main/java/imgui/internal/flag/ImGuiDockNodeState.java

@@ -0,0 +1,11 @@
+package imgui.internal.flag;
+
+public final class ImGuiDockNodeState {
+    private ImGuiDockNodeState() {
+    }
+
+    public static final int Unknown = 0;
+    public static final int HostWindowHiddenBecauseSingleWindow = 1;
+    public static final int HostWindowHiddenBecauseWindowsAreResizing = 2;
+    public static final int HostWindowVisible = 3;
+}