improve moerr to support mo-error's unified format and reporting

[xzxiong]

What type of PR is this?

• [ ] API-change
• [ ] BUG
• [ ] Improvement
• [ ] Documentation
• [x] Feature
• [ ] Test and CI
• [ ] Code Refactoring

Which issue(s) this PR fixes:

issue #3435,

What this PR does / why we need it:

mo has its own error code/message, and need to adapt mysql error code.

• define moErrorMsgItem{errorCode, mysqlErrorCode, errorMsgOrFormat} to handle moErrorCode->mysqlErrorCode mapping rules
• define New(errorCoe, args) and NewWithContext(context.Context, errorCode, args) to handle error reporting
• modify reference of moerr.ErrTxnClosed error, as an example of moerr.New(...)
• predefine Group 6: sql error as sql error, which normally can be converted to mysql error code.