[PoC] API docs refactoring: Include the docstring in the binding code itself replacing the call to the function `get_docstring()`.

[niketagrawal]

Steps

1. Add cpp source in tudat repository, for example, a function to add two numbers.
2. Add the binding code in tudatpy/. Include docstring in the binding code. Skip using generate_docstring(). For example, in this repository https://github.com/pybind/scikit_build_example
3. Build the python extension module for the newly added function and test whether the python module can be imported successfully in the Python interpreter.
4. Build docs and test html files locally.

Since the above proof of concept involves code changes to both tudat and tudatpy, tudat-bundle seems to be the repository to experiment it, however, implementing the above proof of concept in tudat-bundle repository poses the following challenge:

• Code changes to git submodules tudat and tudatpy can't be tracked in the pull request. This will not be a feasible entry point for developers to contribute their changes.

Issues with this approach

• This idea is not scalable for the size of the project as large as tudat. Manually replacing all the docstrings for the bindings from docstrings.h to their corresponding modules in tudatpy/ is not feasible. Automation using a script can solve this problem.

[niketagrawal]

PoC completed. This idea will not be further explored. The approach described in #150 is a better alternative.