Feature Request

Describe your feature request related problem:

Part of #325, After pingcap/ticdc#768 TiCDC support external storage.
we have the ability to generate lots of log backup with TiCDC. but sometimes, the log is too large to apply.
mostly, users prefer a difference backup rather than log backup.
so we can directly translate log backup to sst file.
and this will improve the performance of data recovery.

Describe the feature you'd like:

Support generate difference backup(SST can be restored) with log backup.

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy:

Workload estimation(person-day)

• Design: 1
• Develop: 5
• QA: 3
• Document: 3