[Feature] Support writing to branch during CDC

[JackeyLee007]

Search before asking

• I searched in the issues and found nothing similar.

Motivation

Some time, user want to sync data batchly when CDC task running. And no data overwriting is expected, which means even for the same record (identified by the PK). The late arrived CDC data could not overwrite the offline data.

Solution

Use a dedicated fallback realtime branch for the CDC sinking.
The branch name could be provided with the following option:

--table-branch tablename=branch_name 

Anything else?

No response

Are you willing to submit a PR?

• I'm willing to submit a PR!