[Improve](mysqlSync)Add the configuration of whether to synchronize the default value

[DongLiang-0]

Proposed changes

At present, when the mysql database sync to doris , there is a default value in the field, but the actual data is null, the data cannot maintain consistency.

Like: when mysql schema has a default value and the insertion is null, the data synchronized to doris uses the default value.

CREATE TABLE `test_sink` (
  `id` int NOT NULL,
  `name` varchar(50) DEFAULT 'test_default',
  `age` int DEFAULT '10000',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

insert into test_sink (id,name,age) values(6, null, 666);
insert into test_sink (id,name,age) values(5, 'zhaoliu', null);

Configure --ignore-default-value, the default value will not be synchronized, otherwise it will be synchronized.

Problem Summary:

Describe the overview of changes.

Checklist(Required)

1. Does it affect the original behavior: (Yes/No/I Don't know)
2. Has unit tests been added: (Yes/No/No Need)
3. Has document been added or modified: (Yes/No/No Need)
4. Does it need to update dependencies: (Yes/No)
5. Are there any changes that cannot be rolled back: (Yes/No)

Further comments

If this is a relatively large or complex change, kick off the discussion at dev@doris.apache.org by explaining why you chose the solution you did and what alternatives you considered, etc...

[JNSimba]

params.has is better？

[DongLiang-0]

Thanks for your suggestion, I have fixed it.

[JNSimba]

LGTM