TensorFlow jobs that involve multiple hosts (e.g., parameter-server setups and
TPU coordinator-worker setups) can generate >1 DebugEvent file sets when
instrumented with tfdbg2's `tf.debugging.experimental.enable_dump_debug_info()`.
This CL adds capability to load these multiple file sets belonging to the
same tfdbg_run_id to DebugEventsReader and DebugDataReader.
PiperOrigin-RevId: 317765159
Change-Id: Ifcf593bd8b404e3e1c3a6f3f3be70bd6b8b73555