Rewrite deprecated WinForms MainMenu/MenuItem/ToolBar classes for .NET 8 compatibility

[Copilot]

Summary

Replaces the removed/deprecated System.Windows.Forms classes (MainMenu, MenuItem, ContextMenu, ToolBar, ToolBarButton) with their modern ToolStrip-based equivalents so the GUI SDK compiles and runs on .NET 8+.

Changes

WinForm/MenuToolbar.prg (core rewrite)

• VOMenu now inherits MenuStrip (was MainMenu)
• VOMenuItem now inherits ToolStripMenuItem (was MenuItem)
  • Stores click/select/popup handler delegates as fields for safe cloning
  • CloneMenu() reconstructs a deep copy with all handlers preserved
  • RemoveFromParent() removes from DropDownItems or top-level Items
  • SetShortCut(LONG) sets ShortcutKeys
• VOToolBar now inherits ToolStrip (was ToolBar)
  • ButtonSize property maps to ImageScalingSize
  • GetButton() searches Items collection
• VOToolBarButton now inherits ToolStripButton (was ToolBarButton)
  • Pushed maps to Checked; Rectangle maps to Bounds
• VOSeparator wraps ToolStripSeparator
• AsContextMenuStrip() replaces AsContextMenu() — builds a ContextMenuStrip from cloned items

Menu/Accelerator.prg

• AcceleratorKey.Shortcut now returns System.Windows.Forms.Keys (the Shortcut enum was removed in .NET 5+)

Menu/Menu.prg

• AppendItem / InsertItem: use Items instead of MenuItems; separators create ToolStripSeparator directly
• DeleteItem: uses RemoveFromParent() helper
• GetSubMenu: uses CloneMenu() on the new API
• SetShortCuts / __ClearShortCuts: iterate ToolStripItemCollection using ShortcutKeys / Keys.None
• __CreateMenuItem: wires MouseEnter (was Select) and DropDownOpened (was Popup)
• ShowShortcutKeys replaces ShowShortcut
• Helper functions GetMenuItemCount / GetSubMenu updated

Menu/ToolBar.prg

• OnControlCreated: uses ShowItemToolTips, GripStyle.Hidden, and ItemClicked event
• ItemClicked replaces ButtonClick as the click handler
• AppendItem / InsertItem: separators use VOSeparator, buttons use Items.Add/Insert
• DeleteItem: uses Items.IndexOf + Items.RemoveAt
• ButtonStyle setter: iterates Items.OfType<VOToolBarButton>()
• Flat assign: uses ToolStripRenderMode instead of ToolBarAppearance
• ButtonCount: uses Items.Count
• __CreateButton and __GetButton return typed VOToolBarButton

ResourceReader/ResourceMenu.prg

• AddItemsTo: uses a List<OBJECT> stack; dispatches to Items.Add or DropDownItems.Add based on current context type

Windows/Window.prg

• Menu setter: adds VOMenu to Form.Controls and sets Form.MainMenuStrip
• ContextMenu property: sets Form.ContextMenuStrip
• ContextMenuShow: shows Form.ContextMenuStrip

Windows/ChildAppWindow.prg

• Menu setter: replaces deprecated MdiList/MergeType with Form.MdiWindowListItem

Windows/ShellWindow.prg

• Menu setter: replaces MenuItem.MdiList with Form.MdiWindowListItem

Windows/Application Window.prg

• Activate: replaces oShell:Form.Menu assignment with ToolStripManager.Merge() for MDI menu merging

Controls/Control.prg

• ContextMenu property: sets Control.ContextMenuStrip instead of Control.ContextMenu