Convert openai-asst-webpage-with-functions-js to TypeScript

[mcasalaina]

Converts the OpenAI Assistants Webpage project from JavaScript to TypeScript, including updating dependencies and build configurations.

• Renames and migrates JavaScript files to TypeScript, ensuring type safety and leveraging TypeScript features for better code management.
• Updates the package.json to include TypeScript-specific dependencies and modifies scripts for Vite, replacing Webpack with a more modern build tool.
• Introduces a tsconfig.json for TypeScript compiler options and a vite-env.d.ts for Vite environment types, enhancing the development environment.
• Adjusts the HTML template to reference the new TypeScript entry point and updates the favicon link for consistency.

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