Automatically add empty tabulated ephemeris when needed

[DominicDirkx]

When setting the results of a numerical propagation using the Simulator (https://tudatpy.readthedocs.io/en/latest/numerical_simulation.html#tudatpy.numerical_simulation.SingleArcSimulator, set_integrated_result = true), the propagated body needs to have a compatible ephemeris. If it does not, it crashes at present (with an error?), This can be made more robust by adding an ephemeris 'on the fly'

[DominicDirkx]

Some progress has been made:

https://github.com/tudat-team/tudat/tree/feature/automatic_tabulated_ephemeris

The modifications have been checked with selected unit tests. Modification will not work (yet) for multi- and hybrid-arc

[DominicDirkx]

All unit tests are now passing, but the automatic creation of a tabulated ephemeris (either translational or rotational) is only working for single arc. When using a multi-arc propagation, and wanting to reset the ephemeris, a user still needs to manually define a multi-arc ephemeris in the body that is to be propagated.

Update: considering the fact that @MarieFayolle will be adding some significant additions to the multi-arc propagation, which may influence the solution to this issue, I propose that the above code gets merged now, and the multi- and hybrid-arc auto-ephemeris creation gets added after her work is added.

[SamFayolle]

Hi Dominic, I gave it a look and I completely agree with you that it is better to push the single arc code now and wait for the coming modifications of the multi arc propagation. Especially, one think on my todo list for next week is to modify how to reset ephemerides in the multi-arc case, so I guess it makes perfect sense to wait for those changes.

[DominicDirkx]

Code has been merged :)