refactor: do some internal refactor.

enh: enh chartset convert

fix: interval + fill desc order result different issue

fix: duplicated groups result in group by

fix: fill null value issue

fix(query): avg function support overflow sum value calculate

enh: print ipstr on taos_connect

test: add test cases

fix: skip msg

fix: keepColumnName parameter changes the user alias

fix:modify delete msg type to tmq meta

enh: promp the dnode is already in dropping state while repeat drop it

Fix(tsdb): table block distributed totalSize is zero 

fix(query): set start row index for desc scan.

fix(meta/malloc): use new aligned buffer pool malloc

test: modify test case for checking db ready

fix: invalid interval query result

fix: fix time related function inconsistent result in nested queries