Release Note 1.2.1

## Feature
Support doris catalog #60
Add RowSerializer for datastream #71
Support 'sink.parallelism' config for flinksql #72 #77
Support flink table lookup join #61
Add JsonDebeziumSchemaSerializer for schema change with datastream #79

## Bug
fix enable-delete option bug #63
fix bug when abort fail #78

## Thanks
Thanks to everyone who has contributed to this release:
@caoliang-web
@dinggege1024
@DongLiang-0
@geniusjoe
@huyuanfeng2018
@JNSimba

The issue contains the proposed 1.2.1 release-note sections and references issues #60, #71, #72, #77, #61, #79, #63, and #78, but names no file or test. Review those referenced changes and the repository's release process first; done means the release note is placed or updated in the expected location with accurate feature, bug, and contributor entries.

Written by the indexing model from the issue text.