Structure for the python module

[darioizzo]

The first draft for the python module. This PR will stop at a very early stage with only the structure and a few exposed and documented features.

• CI including python build
• Structure for the python test module
• Structure of the pybind11 core module
• Structure for the docstrings

[codecov-commenter]

Codecov Report

Merging #8 (f44d95f) into main (e59e8e5) will decrease coverage by 0.03%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #8      +/-   ##
==========================================
- Coverage   98.61%   98.59%   -0.03%     
==========================================
  Files          21       21              
  Lines        1156     1206      +50     
==========================================
+ Hits         1140     1189      +49     
- Misses         16       17       +1     

Files	Coverage Δ
include/kep3/core_astro/convert_anomalies.hpp	95.95% <100.00%> (+4.84%)	⬆️
include/kep3/planets/jpl_lp.hpp	100.00% <100.00%> (ø)
src/planets/jpl_lp.cpp	98.42% <100.00%> (-0.82%)	⬇️