Base class from which EditorToolAttribute and EditorToolContextAttribute inherit.
| displayName | 在菜单中显示的名称。 |
| targetContext | If provided, the EditorTool will only be made available when the ToolManager.activeContextType is equal to targetContext. |
| targetType | Set to the type that this EditorTool or EditorToolContext can edit. Set to null if the tool is not specific to a Component and should be available at any time. |