Modify `dataset_type_hierarchy` to support 3 tiers

[maxsibilla]

The UBKG dataset-types endpoint (https://ontology-api.dev.hubmapconsortium.org/dataset-types?application_context=sennet) will be modified to include an analyte field that we will need to grab for each dataset type. The current dataset_type_hierarchy will need to be modified to scale to support 3 tiers.

[maxsibilla]

Simplest solution might be to change the structure to be an array of file paths. Example:

Microscopy/Collagen/Histology
Microscopy/Polysaccharide/Histology

We would need to ensure no slashes exist in the modality, analyte, or dataset type fields.

[maxsibilla]

Proposed solution:

[
  {
    "modality": "Microscopy",
    "analyte": "Collagen",
    "dataset_type": "Histology"
  },
{
    "modality": "Microscopy",
    "analyte":"Polysaccharide",
    "dataset_type": "Histology"
  }
]

[
  {
    "modality": "Spatial Transcriptomics",
    "analyte": "RNA",
    "dataset_type": "Visium (with probes)"
  },
  {
    "modality": "Microscopy",
    "analyte": "Protein",
    "dataset_type": "Visium (with probes)"
  }
]

[maxsibilla]

https://docs.google.com/presentation/d/1ZTSuVMTVpyPdmLA89ehXURZ9wxmowAB0zL3ekmjMX4U/edit?slide=id.g3dff27178a3_0_15#slide=id.g3dff27178a3_0_15

[maxsibilla]

We will utilize this new endpoint: https://ontology-api.dev.hubmapconsortium.org/dataset-types/hierarchy

[libpitt]