![translate](http://www.w3resource.com/PostgreSQL/postgresql-translate-function.png)

Author: zhichao.li <zhichao.li@intel.com>

Closes #7709 from zhichao-li/translate and squashes the following commits:

9418088 [zhichao.li] refine checking condition
f2ab77a [zhichao.li] clone string
9d88f2d [zhichao.li] fix indent
6aa2962 [zhichao.li] style
e575ead [zhichao.li] add python api
9d4bab0 [zhichao.li] add special case for fodable and refactor unittest
eda7ad6 [zhichao.li] update to use TernaryExpression
cdfd4be [zhichao.li] add function translate