Add support for asteroids targets as SPICE body references

RYUGU ID 2162173 SpiceBody.is_valid return an error.

This is due to SpiceBody.is_valid method on this line in spice.references

return int(self) == CODE_BODY_SUN or CODE_BODY_MIN <= int(self) <= CODE_BODY_MAX

that is in turn defined on top CODE_BODY_MAX = 999

The case I am working on is RYUGU, target of Hayabusa2 mission

They defined RYUGU as 2162173 , at the bottom of pck/ryugu_v10.tpc.

I modified the mk in the dataset to my needs : `\begindata

PATH_VALUES = ( '..' ) PATH_SYMBOLS = ( 'KERNELS' )

KERNELS_TO_LOAD = ( '$KERNELS/lsk/naif0012.tls'

                      '$KERNELS/pck/pck00010.tpc'
                      '$KERNELS/pck/ryugu_v10.tpc'
                    
                      '$KERNELS/fk/hyb2_v15.tf'
                      '$KERNELS/fk/hyb2_hp_v01.tf'
                      '$KERNELS/fk/hyb2_ryugu_v01.tf'
                    
                      '$KERNELS/ik/hyb2_nirs3_v03.ti'
                      
                      '$KERNELS/sclk/hyb2_20230214_v01.tsc'

                      '$KERNELS/spk/hyb2_de430.bsp'
                      '$KERNELS/spk/2162173_ryugu_v02.bsp'
                      '$KERNELS/spk/2162173_ryugu_20180601-20191230_0060_20181221.bsp'
                      '$KERNELS/spk/hyb2_20141203-20161119_0001h_final_ver1.bsp'
                      '$KERNELS/spk/hyb2_20141203-20141214_0001m_final_ver1.bsp'
                      '$KERNELS/spk/hyb2_20151123-20151213_0001m_final_ver1.bsp'
                      '$KERNELS/spk/hyb2_20191107-20201202_0001h_final_ver1.bsp'
                      '$KERNELS/spk/hyb2_20201202-20201210_0001m_final_ver2.bsp'
                      '$KERNELS/spk/hyb2_20201210-20201230_0001h_final_ver1.bsp'
                      '$KERNELS/spk/hyb2_20201230-20210524_0001h_final_ver3.bsp'
                      '$KERNELS/spk/hyb2_20210524-20230905_0001h_final_ver1.bsp'
                      '$KERNELS/spk/hyb2_hpk_20180627_20191119_v01.bsp'
                      '$KERNELS/spk/lidar_derived_trj_20191114_no6dofc_v03.bsp'

                      '$KERNELS/ck/hyb2_hkattrpt_2014_v04.bc'
                      '$KERNELS/ck/hyb2_hkattrpt_2015_v04.bc'
                      '$KERNELS/ck/hyb2_hkattrpt_2016_v04.bc'
                      '$KERNELS/ck/hyb2_hkattrpt_2017_v04.bc'
                      '$KERNELS/ck/hyb2_hkattrpt_2018_v04.bc'
                      '$KERNELS/ck/hyb2_hkattrpt_2019_v04.bc'
                      '$KERNELS/ck/hyb2_hkattrpt_2020_v04.bc'
                      '$KERNELS/ck/hyb2_hkattrpt_2021_v04.bc'
                      '$KERNELS/ck/hyb2_hkattrpt_2022_v04.bc'
                      '$KERNELS/ck/hyb2_aocsc_2014_v04.bc'
                      '$KERNELS/ck/hyb2_aocsc_2015_v04.bc'
                      '$KERNELS/ck/hyb2_aocsc_2016_v04.bc'
                      '$KERNELS/ck/hyb2_aocsc_2017_v04.bc'
                      '$KERNELS/ck/hyb2_aocsc_2018_v04.bc'
                      '$KERNELS/ck/hyb2_aocsc_2019_v04.bc'
                      '$KERNELS/ck/hyb2_aocsc_2020_v04.bc'
                      '$KERNELS/ck/hyb2_aocsc_2021_v04.bc'
                      '$KERNELS/ck/hyb2_aocsc_2022_v04.bc'

)

\begintext `