Currently live restore only reports progress at file level granularity. If a file is large then the user may want to know how far through a given file the worker thread is.

To implement this we will largely copy the RTS implementation which logs a progress message every 20 seconds for a given file.

In the progress message we should report:

• The URI
• The number of bytes transferred by the thread. This will give a clear indication if the thread has become stuck.
• The amount of time spent migrating that file.

Optionally report the number of files processed total.