This pull request introduces a new headless Toolbar component suite to the @fluentui/react-headless-components-preview package. It adds the core Toolbar component and related subcomponents (such as ToolbarButton, ToolbarDivider, ToolbarGroup, and ToolbarRadioGroup), along with their hooks, types, and renderers. These components are built on top of the primitives from @fluentui/react-toolbar, exposing a headless API for advanced composition and styling. The PR also adds tests and updates package dependencies.

New Toolbar suite integration:

• Added Toolbar, ToolbarButton, ToolbarDivider, ToolbarGroup, and ToolbarRadioGroup components, each with corresponding hooks (useToolbar, useToolbarButton, etc.), types, and render functions, providing a headless API for building toolbars. [1] [2] [3] [4] [5]
• Extended the public API and type definitions to include all new Toolbar-related components, props, states, slots, and context values, ensuring they are documented and available for consumers. [1] [2] [3] [4]
• Integrated the new @fluentui/react-toolbar dependency to provide base implementations for the Toolbar primitives.

Component implementation details:

• Each Toolbar subcomponent sets appropriate data attributes (e.g., data-vertical, data-disabled, data-icon-only) on the root element to facilitate styling and state indication. [1] [2] [3] [4] [5]
• Render functions for Toolbar subcomponents delegate rendering to the corresponding base component renderers from Fluent UI (e.g., renderButton_unstable, renderDivider_unstable). [1] [2]

Testing:

• Added conformance and rendering tests for the Toolbar component to ensure correct behavior and accessibility attributes.

This update enables advanced headless composition of toolbars and related controls using Fluent UI primitives in the preview package.