GraphQL Client: Add MockedStoryProvider
Created by: umpox
This adds a simple wrapper around <MockedProvider />
to ensure we can reliably mock network responses in Storybook.
Without this, stories would need to directly match the variables
passed to each request. That wouldn't be possible as often our Stories allow dynamic data (e.g, text input)
There's arguably more we can do here, (e.g. stricter mock matching), but this should cover 95%+ of cases for now!