MockNetworkInterface match mock requests regardless of variable order

[L1fescape]

Currently mock data needs to exactly match the request being made within a component being tested. This is because requests object are stringified and used as keys when registering and looking up the corresponding response objects to be returned. This change sorts the request object when it is stringified so the order of variables doesn't matter.

This issue is discussed in #674

[apollo-cla]

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[mention-bot]

@L1fescape, thanks for your PR! By analyzing the history of the files in this pull request, we identified @jbaxleyiii, @calebmer and @mmissey to be potential reviewers.

[jbaxleyiii]

@L1fescape thank you! This looks great to me!