This PR migrates the SPICE L2 FITS reader function(s) and SPICEMeta class from sunraster to sospice.
To Do
[ ] Wait for ndcube v2.3 release which will include a new sliceable metadata object.
[ ] Wait for new release of sunraster which will adapt underlying infrastructure of SpectrogramCube.instrument_axes to use new sliceable metadata object.
[ ] Alter read_spice_l2_fits to put the instrument_axes information into the metadata object.
This PR migrates the SPICE L2 FITS reader function(s) and
SPICEMetaclass fromsunrastertosospice.To Do
SpectrogramCube.instrument_axesto use new sliceable metadata object.read_spice_l2_fitsto put theinstrument_axesinformation into the metadata object.