Fix TiDB behavior: constraint check

[tangenta]

Index issue: #598

SQL example

CREATE TABLE t (a INT CHECK (a > 1));
ALTER TABLE t ADD CONSTRAINT crn CHECK (a > 1);
ALTER TABLE t ALTER CHECK

Current implementation

ColumnOptionCheck, ConstraintType.ConstraintCheck, AlterTableAlterCheck, and AlterTableDropCheck are ignored by TiDB.

Expected implementation

Throw a warning.

[chanme]

@tangenta , I'm trying to solve this issue as a new contributor. where should I throw a warning, in pingcap/parser or pingcap/tidb? (I think it should be fixed in pingcap/tidb, but the issue is under pingcap/parser, a bit confused)

[tangenta]

@chanme It should be fixed in pingcap/tidb :)

[chanme]

I have almost finished solving this issue, during writing the unit tests, I find out that some warnings are already generated by the pingcap/parser repo, should I first make a PR to remove the warning in the parser then add warning in pingcap/tidb to solve this issue?

Original Warning is:
| Warning | 1064 | You have an error in your SQL syntax; check the manual that corresponds to your TiDB version for the right syntax to use line 1 column 36 near ")"The CHECK clause is parsed but ignored by all storage engines.