Convert <ViewInstance> to use data from GraphQL query

As discussed in the comments to STSMACOM-73, the Inventory module's <ViewInstance> component, on the graphql branch, currently fetches the relevant instance record twice: once with stripes-connect and once with GraphQL. And it uses the former to populate its display.

As part of the process of moving to GraphQL, we need to modify <ViewInstance> so it displays the data from GraphQL rather than that from stripes-connect; and eventually, it will become possible to remove the stripes-connect code, as I have already done for <Instances>.

Once that is done, it will be possible to proceed, with a better understanding, towards the actual mutations in <InstanceForm>.