fix(parity): rsync bwlimit units, --info categories, --ignore-errors deletion semantics

- --bwlimit: faithful port of rsync 3.4.1 parse_size_arg (default KiB/s,
  binary K/M/G/T/P, decimal KB/MB, KiB/MiB, decimals, 0 = unlimited, 512-byte
  floor, (size+512)/1024 quantization).  Unit tests + docs.
- --info: wire del/remove/name/flist/nonreg/progress to real FastSync events in
  rsync's line format (deleting PATH, sender removed NAME, name lines,
  'sending incremental file list', skipping non-regular file "NAME"); name no
  longer aliases copy; --info=progress drives the progress path and report_stats.
- --ignore-errors: match rsync's default -- a source I/O error skips deletion
  unless --ignore-errors, while the readable tree still transfers and the run
  exits 23.  Covers all delete timings and both send paths.

src/shared/protocol.c

@@ -183,6 +183,10 @@ void io_set_bwlimit(unsigned long long bytes_per_sec) {
   mtx_unlock(&bw_mutex);
 }
 
+unsigned long long io_get_bwlimit(void) {
+  return global_bwlimit();
+}
+
 void protocol_session_set_bwlimit(ProtocolSession* session, unsigned long long bytes_per_sec) {
   if (!session)
     return;