Support custom function spaces in LFRic (multi-data fields, different number of layers and data)

[TeranIvy]

Relevant LFRic documentation is in this LFRic wiki.

Update: The support will require a redesign of function space representation. See this new LFRic wiki.

[TeranIvy]

• [ ] Metadata parsing support and related documentation. LFRic design wiki for metadata.
• [ ] Kernel arguments for fields on column (declarations, call argument list, stub argument list). LFRic design wiki for fields on column.
• [ ] Kernel arguments for fields on domain (declarations, call argument list, stub argument list). LFRic design wiki for fields on domain.
• [ ] Kernel arguments for operators (declarations, call argument list, stub argument list).
• [ ] Kernel argument lists for basis functions/quadrature (declarations, call argument list, stub argument list).