Nyx shall switch to the principal axes frame of the Moon for harmonics computations

[ChristopherRabotin]

For this task, the idea is to demonstrate that Nyx supports high fidelity estimation of lunar orbits.

Idea: grab one of the definitive ephemeris files from NASA PDS for LRO, cf https://naif.jpl.nasa.gov/pub/naif/pds/data/lro-l-spice-6-v1.0/lrosp_1000/data/spk/. Take an arbitrary state, and generate some synthetic measurements using the truth trajectory. Start the OD process estimating the Cr, and using a high gravity field for the overall process. Ensure that the definitive ephem can be rebuilt close enough to be usable.

Things to note here: the ephem uses an old DE file. The Cr will likely need to be estimated because it can't probably be quickly found online. The gravity field used to build the real definitive ephem may not be the JGGRX model from GRAIL.