Added missing pages to React and Svelte5 playrounds

[Verox001]

Added Async and Poll Page to React and Svelte5 Playgrounds to properly test the new features

[Verox001]

This pull request includes the addition of new components and pages for both React and Svelte applications to handle asynchronous operations and polling. The most important changes include the creation of TestGrid and TestGridItem components, as well as the addition of Async and Poll pages.

New Components:

• playgrounds/react/resources/js/Components/TestGrid.tsx: Added TestGrid component to create a grid layout.
• playgrounds/react/resources/js/Components/TestGridItem.tsx: Added TestGridItem component to display individual items within the grid.
• playgrounds/svelte5/resources/js/Components/TestGrid.svelte: Added TestGrid component for Svelte with slot support.
• playgrounds/svelte5/resources/js/Components/TestGridItem.svelte: Added TestGridItem component for Svelte with slot support.

New Pages:

• playgrounds/react/resources/js/Pages/Async.tsx: Added Async page to handle asynchronous operations with various state checks.
• playgrounds/react/resources/js/Pages/Poll.tsx: Added Poll page to demonstrate polling functionality with user and company data.
• playgrounds/svelte5/resources/js/Pages/Async.svelte: Added Async page for Svelte to handle asynchronous operations and form submissions.
• playgrounds/svelte5/resources/js/Pages/Poll.svelte: Added Poll page for Svelte to demonstrate polling functionality and async redirects.