* [TD-5872]<fix>: taosdemo stmt improve.

* refactor stmt functions.

* [TD-5872]<fix>: taosdemo stmt csv perf improve.

* rand func back to early impl.

* fix windows/mac compile error.

* fix empty tag sample.

* [TD-5873]<test>add stmt’performance taosdemo testcase
Co-authored-by: NShuduo Sang <sdsang@taosdata.com>
Co-authored-by: tomchon <haoran920c@163.com>