add getVariable() to util/sql.py

add 4 testcases to query/queryWildcardLength.py

leave a uncorrelated bug ---> TD-5918

* [TD-3048]<feature>: support lines/stream/query_a/stop_query/ and so on.

commit 0edc106a76a95b28e65019c2ee4e4ed84530ad35
Author: Huo Linhe <linhehuo@gmail.com>
Date:   Thu Jul 29 21:13:13 2021 +0800

    doc: improve document for python connector

commit 84915de0831b49c8378a16242dd0dbba8aaf386f
Author: Huo Linhe <linhehuo@gmail.com>
Date:   Thu Jul 29 20:35:45 2021 +0800

    chore: add time elapsed

commit 1e8822e01bda96388a359363776792e261260b88
Author: Huo Linhe <linhehuo@gmail.com>
Date:   Thu Jul 29 20:26:01 2021 +0800

    feat: support multi bind

commit 82d823f6194471fd3324b50f7dfba0ee9f10a7dd
Author: Huo Linhe <linhehuo@gmail.com>
Date:   Thu Jul 29 16:42:05 2021 +0800

    feat: python support for async query and subscribe with callback

commit 8b9d36de2945906821225189cb47958e153d81e2
Author: Huo Linhe <linhehuo@gmail.com>
Date:   Wed Jul 28 18:09:09 2021 +0800

    feat: finish stream and stmt interface

commit bc871aa43e9fc28dd1b3f8784a8ac6ee988564b5
Author: Huo Linhe <linhehuo@gmail.com>
Date:   Mon Jul 26 20:21:27 2021 +0800

    feat: basic full-fetured implementations

commit e5f7a5213e9016c377a57485e8d5c12139ce0957
Author: Huo Linhe <linhehuo@gmail.com>
Date:   Fri Jul 23 10:33:14 2021 +0800

    tmp: refactor

* chore: fix insert/line_insert.py error

* [TD-3048]<fix>: fix tests error

* [TD-3049]<feature>: support stop_query in python connector cursor

* [TD-3048]<doc>: improve python connector document

* [TD-3048]<doc>: improve python connection README

* [TD-3048]<hotfix>: fix python2 install and runtime error

* chore: replace insertLines with insert_lines

* chore: fix misspellings

* chore: fix crash gen error in threading

* feat: support __del__ method for simplify

* test: fix subscription test result check

* chore: compatible with 2.0.20

* chore: fix python connector subscription test case

* [TD-3048]<fix>: fix schemaless insert test

* [TD-3048]<fix>: fix memory leak in crash_gen test case

* [TD-3048]<fix>: minor fix for crash gen memory leak

* [TD-3048]<fix>: set minimal required python3 as 3.4

* chore: update version in setup.py

* [TD-3048]<fix>: fix runtime errors in python3.4

* [TD-3048]<fix>: add typing as a dependency

add method in util/sql.py---getColNameList() and checkColNameList

add testcase query/queryCnameDisplay.py

* [TD-4752]<feature>: python connector support nanosecond.

* [TD-4752]<feature>: support nanosecond in test framework.

return integer for nanosecond in connector since python does not support nanosecond yet.

By this commit, It will close TD-3639.

It will not require test case to write *correct* datetime string to pass
a test case. One test could use seconds, milliseconds or microseconds to
check data.

That means the three tests are equivalent:

```python
.checkData(0, 0, "2020-01-01 00:00:00")
.checkData(0, 0, "2020-01-01 00:00:00.000")
.checkData(0, 0, "2020-01-01 00:00:00.000000")
```
Co-authored-by: NHuo Linhe <linhehuo@gmail.com>

By this commit, It will close TD-3639.

It will not require test case to write *correct* datetime string to pass
a test case. One test could use seconds, milliseconds or microseconds to
check data.

That means the three tests are equivalent:

```python
.checkData(0, 0, "2020-01-01 00:00:00")
.checkData(0, 0, "2020-01-01 00:00:00.000")
.checkData(0, 0, "2020-01-01 00:00:00.000000")
```

disable telemetry reporting in test.
fix other telemetry related bugs.