ENH: add Series.info
- [x] initial draft to close #5167
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

screenshot of the example
![image](https://user-images.githubusercontent.com/33491632/74069703-f1754b80-49f6-11ea-8c9e-8ec4e16166f1.png)

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Note to self: this change from `ba72b59b44f15076877e784e16cbc66aa03e0adc` breaks the tests

```diff
-    # groupby dtype.name to collect e.g. Categorical columns
-    counts = data.dtypes.value_counts().groupby(lambda x: x.name).sum()
+    counts = data._data.get_dtype_counts()
```

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### Updated

Currently, looks like this:

![image](https://user-images.githubusercontent.com/33491632/86509914-7a948100-bde3-11ea-84fb-907df7a2a40c.png)
