MDEV-34705: Binlog-in-engine: Implement file header page

Now the first page of each binlog tablespace file is reserved as a file
header, replacing the use of extra fields in the first gtid state record of
the file. The header is primarily used during recovery, especially to get
the file LSN before which no redo should be applied to the file.

Using a dedicated page makes it possible to durably sync the file header to
disk after RESET MASTER (and at first server startup) and not have it
overwritten (and potentially corrupted) later; this guarantees that the
recovery will have at least one file header to look at to determine from
which LSN to apply redo records.

Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>

mysql-test/suite/binlog_in_engine/recovery.test

@@ -57,6 +57,6 @@ EOF
 --source include/wait_until_connected_again.inc
 
 --let $binlog_file=
---let $binlog_start= 0
+--let $binlog_start= 4
 --source include/show_binlog_events.inc
 DROP TABLE t1;