fix: column comment is not supported

refactor: do some internal refactor.

fix: add stmt error handling

fix: aovid conn leak

ehn(plan/optimizer): remove tbname fetching with cached groupby

fix(query): fix interp tsdbReader external range not setting properly

fix coverity scan problem

enh: last_row is keep order function

* fix: taosbenchmark multithreads with limit for main

* fix: update taos-tools

Feature/3 liaohj

enh: convert the month and year in interval-offset to a database precision duration

fix: error in optimizing useless columns for multi-level set operators

fix(tmq): build sync api on top of async APIs.

fix: task context not exists issue