Update use of /metadata-graph endpoint in web-registry

[blushi]

As part of https://github.com/regen-network/registry-server/pull/168, we've flattened the response from the /metadata-graph endpoint, the data doesn't come wrapped inside some metadata field anymore so we should update the front-end to account for that.

Ref: https://github.com/regen-network/registry-server/pull/168#pullrequestreview-941394778

cc/ @mhagel @wgwz

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[wgwz]

@blushi @mhagel i'd enjoy taking this issue as a way of gaining some experience in regen-web

[blushi]

@wgwz sure!