Support start task with inconsistent upstream table schema for Optimsitic Sharding DDL

[GMHDBJD]

Is your feature request related to a problem?

When users have some inconsistent sharding tables, they can not start a task either in pessimistic mode or optimistic mode.

Describe the feature you'd like

start task with inconsistent upstream table schema for Optimsitic Sharding DDL
e.g.

table1(a int primary, b int)
table2(a int primary, c int)

Describe alternatives you've considered

No response

Teachability, Documentation, Adoption, Migration Strategy

To support different upstream table schema when tasks start, master need to know all upstream schema for a optimstic DDL.
The main logic may like

start-task
worker put all upstream table names which needed for the task to etcd
master watch table names and save to memory
worker fetch table infos from dump files or upstream databases and then flush to downstream checkpoint when entering sync unit
master receive a DDL and then fetch all sharding table infos from downstream for that DDL
master joined table base on all table infos
master return ddl to worker

When stop-task for a source, all the table infos/ddl infos/operations for that source in memory or etcd will be removed.