feat: add cloudsql mysql source and tool

[Yuan325]

Add CloudSQL for MySQL source and tool.

CloudSQLMySQL source is initialize with the following config:

sources:
    my-cloudsqlmysql-source:
        kind: cloud-sql-mysql
        project: my-project-name
        region: my-region
        instance: my-instance-name
        user: my_user
        password: my_pass
        database: my_db
        # ipType: public # The default dialect is public.

MySQL tool is initialize with the following config.

tools:
    test_tool:
        kind: mysql
        source: my-cloudsqlmysql-source
        description: >
            Testing tool.
        statement: "SELECT 1;"