prepare for 3.0

[TD-13052]

Ref: [TD-16627](https://jira.taosdata.com:18080/browse/TD-16627)

Ref: [TD-16627](https://jira.taosdata.com:18080/browse/TD-16627)

* test: add test case for TS-1613

* fix: fixed connection error if -h was used

* fix: assign port if -P is specified

* fix: windows read env
Co-authored-by: NPing Xiao <pxiao@taosdata.com>
Co-authored-by: Nxywang <xywang@taosdata.com>
Co-authored-by: NYang Zhao <yzhao@taosdata.com>

fix: added upstream check to avoid crash

enh: optimize diff_function and remove assert 

[TS-1616]

for 2.6

* enh: taos shell support cloud 2.6

* enh: taos shell support cloud (#13879)

* enh: support url in commandline taos shell

* fix: normal host logic

* enh: add default -R if env var set

* fix: refine taos shell cloud service

* fix: improve user friendly

* fix: add cloud tcp connection

* fix: header file

* fix: add other os

docs: correct TAOS CLI to TDengine CLI

fix(query): V26 fixed group by col_proj_function des error on client. 

for 2.6

[TD-16517]

build: release script modify #TS-1573

docs: move delete data from developer guide to sql reference guide

docs: refine keywords section and add delete keywords

docs: move docs-cn and docs-en to docs