support parsing SHOW REPLICAS for mysql

[tuichenchuxin]

Hi community,

This issue can be a good first try.

Aim

support parse mysql administration statements sql SHOW REPLICAS

Basic Qualifications

• java
• maven
• antlr4

Detail

Add antlr rule in DALStatement.g4. refer to https://dev.mysql.com/doc/refman/8.0/en/show-replicas.html
Implement the visit method in shardingsphere-sql-parser/shardingsphere-sql-parser-dialect/shardingsphere-sql-parser-mysql/src/main/java/org/apache/shardingsphere/sql/parser/mysql/visitor/statement/impl/MySQLDALStatementSQLVisitor.java
To complete this issue, I think we should complete these steps:

• Create anltr rule in DALStatement.g4
• Create MySQLShowReplicasStatement class in this package org.apache.shardingsphere.sql.parser.sql.dialect.statement.mysql.dal
• Add rule in shardingsphere-sql-parser/shardingsphere-sql-parser-engine/src/main/java/org/apache/shardingsphere/sql/parser/core/database/visitor/SQLVisitorRule.java
• Implement the visit method in shardingsphere-sql-parser/shardingsphere-sql-parser-dialect/shardingsphere-sql-parser-mysql/src/main/java/org/apache/shardingsphere/sql/parser/mysql/visitor/statement/impl/MySQLDALStatementSQLVisitor.java.
• Finally, add test for parse clone statement in shardingsphere-test module

Example FYI

• Refer to this merged pr：https://github.com/apache/shardingsphere/pull/12979/files

[dongzl]

I will try it.