feat(parity): wire-stats protocol 2.25.0 + out-format %b/%c/%C

Bump PROTOCOL_VERSION to 2.25.0 and append a report_stats bool to the
config frame, add a STATUS_STATS status, and add process-wide wire byte
counters (protocol_bytes_written/read) for the client.

Render the rsync 3.4.1 --out-format %b (wire bytes sent) and %c (wire
bytes read back) tokens from per-file counter deltas, and %C (whole-file
xxh128 checksum, seed 0) via a new streaming checksum_digest_file().

tests/integration/test_fault_injection.py

@@ -36,7 +36,7 @@ from common import (  # noqa: E402
     verify_transfer,
 )
 
-PROTOCOL_VERSION = b"2.23.0"
+PROTOCOL_VERSION = b"2.25.0"
 STATUS_MANIFEST = 5
 STATUS_OK = 0