Implement File Upload Progress Indicator

Currently, large file transfers occur without clear progress feedback. A progress indicator would greatly improve user experience by showing the percentage or status of an ongoing upload or download event.

Goals:
• Track file transfer progress in real time.
• Display a clear progress bar (circular or linear) to both the sender and receiver.
• Provide a user-friendly representation of how long a file transfer will take.

Possible Approach:
• During file upload, track the number of bytes transferred vs. total bytes.
• Utilize flutter_nearby_connections and Streams and Global cache.
• Update the UI with the calculated percentage (bytes transferred / total bytes).
• Create a callback or event handler that notifies the UI for each chunk of data transferred.
• Handle edge cases like transfer failures or cancellations and gracefully stop the progress bar.