### What problem were solved in this pull request?
Problem:
parse_defs中的一些变量命名不是很清晰

### What is changed and how it works?
重命名，增加SqlNode后缀，希望看起来更清晰，知道这些变量的意图
另外，增加了一个visual studio code的生成parser的任务

logical plan & physical plan;
explain;
yacc rewrite;
join operator(nested loop join);
simple rewrite rules;
fix some issues of mysql protocol;

tested by mariadb ( Ver 15.1 Distrib 5.5.65-MariaDB, for Linux (x86_64) using readline 5.1)
but failed with obclient