ENH: do not sort resulting columns when sort=False
- [x] closes #17041
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

Currently, `pivot_table` sorts the resulting columns even when `sort=False`. For example, the following code snippet produces the column ["age", "height"] in alphabetical order instead of the order in the original `df` or passed by `values=`. 

```py
import pandas as pd

df = pd.DataFrame(
    {
        "firstname": ["John", "Michael"],
        "lastname": ["Foo", "Bar"],
        "height": [173, 182],
        "age": [47, 33],
    }
)
result = df.pivot_table(index=["lastname", "firstname"], values=["height", "age"], sort=False)
print(result)
```

```
                    age  height
lastname firstname             
Foo      John        47     173
Bar      Michael     33     182
```

This PR fixes this issue by not sorting the resulting columns when `sort=False`

FYI, #17041 has some discussion about the order of the columns. PR #40954 added the keyword `sort` to `pivot_table` and was merged in v1.3. 
Hello @ShawnZhong! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:





There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2022-05-15 18:21:51 UTC I think ok to close https://github.com/pandas-dev/pandas/issues/17041 with this PR (if you can add a test for this).

also pls add a whatsnew note. put in reshaping bug fixes section for 1.5 I have added the whatsnew note and changed the PR description to close the issue. 

Is there a specific case that you want me to add a test for?  thanks @ShawnZhong 