added arctan, arccos and arcsin functions and an example file using them

[rimjhimittal]

Changes i have made:

1. Using regular expressions in the following function to address the issue where the replacement code confuses "tan" with "arctan".
   

   MDF/src/modeci_mdf/functions/standard.py

   Line 62 in ca4843a

   def create_python_expression(expression_string: str = None) -> str:

2. Added Functions for arctan, arcsin and arccos in standard.py.

3. Added an example file called arc_functions.py that tests all the three functions.

4. Addressed an import error for "types".

[pgleeson]

Thanks @rimjhimittal. As opposed to adding a python script to demonstrate this in the examples folder, could you add to the test case here: https://github.com/ModECI/MDF/blob/main/tests/test_mdf_functions.py, with usage of your new functions to test that they behave as expected.

[rimjhimittal]

Hey @pgleeson , I have added the test cases. I ran them, they all passed. Should I delete the python script I added to the examples folder?

[pgleeson]

Hi @rimjhimittal. Yes, please delete the python script and image from the examples folder and just use the test. A more comprehensive example showing all the standard built in functions can be added at a later date.

[rimjhimittal]

Okayy, I have removed them both.