Feature Request

Is your feature request related to a problem? Please describe:

Describe the feature you'd like:

Lightning physical mode imported data can set the 17th bit of the field txn_sourece to indicate it's source, this is helpful for downstream systems such as TiKV-CDC to do some special handling on the data, such as skip the data.

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy: