Add F/L commitSeq and commitTs for get_lag

[wyxxxcat]

apache/doris#46769
default

{"success":true,"lag":0,"first_commit_seq":0,"last_commit_seq":0,"first_binlog_timestamp":"1970-01-01 08:00:00","last_binlog_timestamp":"1970-01-01 08:00:00","time_interval":0}

example

{"success":true,"lag":3,"first_commit_seq":40346,"last_commit_seq":40348,"first_binlog_timestamp":"2025-01-17 17:52:21","last_binlog_timestamp":"2025-01-17 17:52:22","time_interval":1}

{"success":true,"lag":2,"first_commit_seq":40348,"last_commit_seq":40368,"first_binlog_timestamp":"2025-01-17 17:52:22","last_binlog_timestamp":"2025-01-17 17:53:07","time_interval":45}