Specify if data object is 4D seismic

[perolavsvendsen]

Data model should support quick identification of data objects that are 4D seismic. E.g. separate 4D from 3D seismic.

Related to/triggered by:

• Filter cases by object type, content etc. fmu-sumo#324

Options:

1. Split current data.content seismic into seismic3D and seismic4D
   • Breaking change
2. Add data.seismic.dimensionality (enum) with allowed values (1, 2),3 and 4 [🟢 preferred!]
   • If only applicable to seismic
3. Add data.dimensionality (enum) (optional) with allowed values as above.
   • If applicable to other data types also, e.g. surfaces
   • Ensure a reliable way to distinguish surface items with elevation values (2,5D grids) and property values (color mapping) #369

[mferrera]

Closing this per discussion in equinor/fmu-sumo#348 and offline discussion. Relevant commentary was that 4d seismic is not really a data type unto itself but an interpretation of more than one 3d data type.