move from graphql API requests to gnomAD toolbox

[bradwbradw]

I'm finding the gnomad graphQL API requests quite unreliable. I'm hoping that the gnomAD toolbox does a better job at retrieving variant frequency information.

Edit variome_backend/library/views/variant.py to populate the gnomadFrequencies using data fetched from gnomAD toolbox. Use the existing code (local DB) as a fallback, in case the gnomAD service goes down. In this case, populate errors with a note that indicates the fallback was used.

Make sure the toolbox provides feature parity with what we already have (for example):

    "gnomadFrequencies": {
        "id": 124,
        "variant": {
            "id": 124,
            "variant_id": "22-27039615-T-C",
            "var_type": "SNV",
            "filter": "abc, def"
        },
        "af_tot": "0.9005720000",
        "ac_tot": 137076,
        "an_tot": 152210,
        "hom_tot": 61788,
        "hemi_tot": 0
    },

If any prop is missing, stop work and let me know.

The graphQL code that this makes obsolete is in frontend/src/pages/variant.jsx - make sure we acheive everything that code acheived.

refs:

• https://github.com/broadinstitute/gnomad-toolbox
• https://broadinstitute.github.io/gnomad-toolbox/api_reference/filtering/variant.html
• https://broadinstitute.github.io/gnomad-toolbox/api_reference