**What type of PR is this?**
- [x] Feature

**What this PR does / why we need it:**
This PR supports boolean expression as DSL.
1. The goal of this PR is to support predicates
    like `A > 3 && not B < 5 or C in [1, 2, 3]`. 
2. Defines `plan.proto`, as Intermediate Representation (IR) 
    used between go and cpp. 
3. Support expr parser, convert predicate expr to IR
    in proxynode, while doing static check there
4. Support IR to AST in cpp, enable the execution