Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

[TD-4056]<fix>: fix possible char string buffer length overflow

* [TD-3976]<fix>: taosdemo print each insert performance data.

* [TD-3976]<fix>: taosdemo print insert performance per thread.
Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

* [TD-4035]<fix>: taosdemo more checking for prevent value out of scope.

* [TD-4035]<fix>: taosdemo more checking for prevent value out of scope.

change min rows and max rows to unsigned int and 0 means default.

* [TD-4035]<fix>: taosdemo more checking for prevent value out of scope.

change offset=0 to get all childtable count
Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

* [TD-4054]<fix>: taosdump wrong column note length.

* [TD-4054]<fix>: taosdump wrong column note length.

reserve 2 bytes for NCHAR.

[TD-4000] <test> verify teature of TD-3948

Origin/td 3614

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>