issue: #38399
- Add a pchannel level checkpoint for flush processing
- Refactor the recovery of flushers of wal
- make a shared wal scanner first, then make multi datasyncservice on it
Signed-off-by: chyezh <chyezh@outlook.com>
issue: #33285
- support transaction on single wal.
- last confirmed message id can still be used when enable transaction.
- add fence operation for segment allocation interceptor.
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Signed-off-by: chyezh <chyezh@outlook.com>