Work package to handle spatial omics data

[mauerk]

Currently, the metadata schema cannot handle submissions of spatial omics experiments. It needs additional enums and probably fields to describe the sample type and the experimental method.

For now:

• SampleTypeEnum: add enum "tissue_sections_rna"
• LibraryPreparationKit: add enum(s) for Xenium
• InstrumentModel: add enum for Xenium
• FlowCellType: add enum(s) for Xenium