Input Action Mapping & Shortcut Customization UI

[alemuntoni]

This PR completely overhauls how input shortcuts are managed and introduces a fully featured Qt UI to let users view, edit, and serialize custom key bindings in the Settings Dialog.

Key Features & Changes:

• New InputActionMap Architecture: Replaces the old BindingMap with InputActionMap and AbstractInputActionMap, providing a much more flexible infrastructure for input filtering and mapping.
• Shortcuts Settings Tab: Introduces a new tab in the SettingsDialog with a dedicated UI (InputBindingsWidget & ShortcutButton) to view and customize keyboard and mouse shortcuts.
• Enhanced Shortcut Support:
  • Allows assigning multiple shortcuts to a single action.
  • Adds the ability to completely disable specific actions.
  • Implements collision warnings when users try to assign a shortcut that is already in use.
• Double Click & Mouse Atomic Actions: Introduces proper management for double click inputs and mouse atomic actions (e.g., focus), fixing drag event distinctions between single and double clicks.
• Serialization & Persistence: Custom shortcuts can now be serialized and deserialized to/from the configuration file, allowing user preferences to persist across sessions.
• Refactoring & Cleanups:
  • Action maps are now cleanly exposed and integrated across all settings classes (ViewerSettings, TrackballSettings, SelectionEditorSettings, MeshSelectorEditorSettings).
  • Embedded actions in AbstractViewerDrawer have been moved to global actions.