All suggeted changes within additional time limit tests (#1815)

* With all suggested changes :white_check_mark: 

possibly covered all the recommended guidelines

* Updated with both slow and faster algorithms

possibally covered all the recomendations

* removed the time comparision part!

* Update data_structures/stacks/next_greater_element.py

Co-Authored-By: Christian Clauss <[email protected]>

* Update data_structures/stacks/next_greater_element.py

Co-Authored-By: Christian Clauss <[email protected]>

* Update data_structures/stacks/next_greater_element.py

Co-Authored-By: Christian Clauss <[email protected]>

* Update data_structures/stacks/next_greater_element.py

Co-Authored-By: Christian Clauss <[email protected]>

* Add benchmark using timeit

https://docs.python.org/3/library/timeit.html

The performance delta between these two implementation is quite small...
```
next_greatest_element_slow(): 1.843442126
     next_greatest_element(): 1.828941414
```

* Optimize slow() to create fast() - Three algorithms in the race

Three algorithms in the race

* Use a bigger test array with floats, negatives, zero

* Setup import next_greatest_element_fast

Co-authored-by: Christian Clauss <[email protected]>