Nereids(new optimizer) code base
Nereids is new query planner for Doris. It include three main parts: parser, analyzer and optimizer.
The parser, generated by ANTLR4, transforms SQL into a logical plan with a tree structure. Analysis and optimization are performed on the logical plan of the tree structure. Each transformation is defined as a rule. The rule is applied to the logical plan using pattern matching. The implementation of the optimizer follows the approach in the Cascades paper.
In #8319, I remove mysql-connector-java dependency because of license incompatibility.
But we need a mysql compatible driver for http query api. So I choose mariadb-java-client,
which is under LGPL.
