test: add cast and varchar case

fix(query): fix the crash caused by the complex having clause in which an scalar function is nested with an aggregate function in group by query.

fix: make taos_options work

feat(udf): UDF service refactoring with new interface

feat(query): a new builtin aggregate function is added.

fix(query): avoid the output result overlap within the project operator buffer.

feat: delimit the time range according to the filtering conditions

refactor(query): refactor string functions 

feat: trow refactor

refactor: vnode