fix(DDL): improve nested functional index support · Pull Request !504 · openEuler/cantian-connector-mysql

# fix(DDL): improve nested functional index support

**[Background]**
* In previous test case, query like below may fail:
```
create table t1(j json, key i1((lower(json_value(j, '$' returning char(10))));
```

**[Root Cause]**
* In `ha_ctc_ddl.cc`, we use a simple for-loop to get the dependent column name from functional index expression, which is causing functional index not able to find this column name.
* Previously we use a regex to rewrite SQL query from MySQL to adopt with ctsql, the compute engine on cantian side. - which could be problematic if DBA use a on-purpose column name/table name that follow a similar pattern to charset encoding.

**[Changes Made]**
* Replace the for-loop with a recursively iterate method.
* Replace the regex-based rewriter with a printer based one. (and we will fallback to normal regex replaced version if we can't access necessary information in non-normalized mode)

**[Test Result]**

* not normalized mode in cantain:
![输入图片说明](https://foruda.gitee.com/images/1741263011252282092/6000021e_8431893.png "屏幕截图")
![输入图片说明](https://foruda.gitee.com/images/1741263051623762748/179226af_8431893.png "屏幕截图")
![输入图片说明](https://foruda.gitee.com/images/1741263068512408096/e5c71f11_8431893.png "屏幕截图")
  * mtr result:
![输入图片说明](https://foruda.gitee.com/images/1741263083194991680/76ed4ca4_8431893.png "屏幕截图")

* normalized mode:
![输入图片说明](https://foruda.gitee.com/images/1741263105982231350/54de452d_8431893.png "屏幕截图")

类型	指派人员	状态
审查	openeuler-ci-bot	已完成 (0/0人)
测试	openeuler-ci-bot	已完成 (0/0人)

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