SQLParserDelegate不能解析DDL语句中的FOREIGN KEY

```
CREATE TABLE IF NOT EXISTS `test_table_normal`(
scoreID INTEGER NOT NULL PRIMARY KEY,
stuID INTEGER NOT NULL,
KEMUID INTEGER NOT NULL,
score FLOAT,
FOREIGN KEY SCORE_ID_FK (stuID) REFERENCES students (stuid),
CONSTRAINT CHK_SCORE_ZIP CHECK (SCORE > 0)
);
```
```
ALTER TABLE test_table_normal
ADD FOREIGN KEY (stuID)
REFERENCES Persons(stuID);
```
报错：
```
java.sql.SQLSyntaxErrorException: You have an error in your SQL syntax; Error occurs around this fragment: {FLOAT,
FOREIGN KEY SCORE}. Error cause: unsupportted column definition
at com.alibaba.cobar.parser.recognizer.SQLParserDelegate.parse(SQLParserDelegate.java:155)
at com.alibaba.cobar.parser.recognizer.SQLParserDelegate.parse(SQLParserDelegate.java:160)
at com.alibaba.cobar.parser.recognizer.SQLParserDelegate.parse(SQLParserDelegate.java:164)
at com.alibaba.cobar.parser.recognizer.SQLParserDelegateTest.testCreateAndDropTable(SQLParserDelegateTest.java:157)
```

Start with SQLParserDelegate.java around the reported parse failure at line 155, then inspect SQLParserDelegateTest.java and testCreateAndDropTable around line 157. Run the supplied CREATE TABLE and ALTER TABLE statements as regression cases; done means both FOREIGN KEY forms parse without the unsupported column definition error.

Written by the indexing model from the issue text.