Add handling of Infura "blocked" status

[Gudahtt]

Description

The network controller has been updated to detect when connecting to an Infura network fails due to the user being blocked. A new status has been added to reflect this state, and two events have been added (one for when a user is blocked, and one for when they are unblocked).

This status and these events are used by the extension to better explain why the network is not working in this scenario.

Changes

• BREAKING: The network status will now be "blocked" rather than "unavailable" when the user is blocked by Infura
• ADDED: The events "infuraIsBlocked" and "infuraIsUnblocked" have been added

References

Fixes #1200

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation for new or updated code as appropriate (note: this will usually be JSDoc)
• I've highlighted breaking changes using the "BREAKING" category above as appropriate

[mcmire]

This looks good to me. One thing I'm noticing is that the unit tests here don't seem to be as exhaustive as the ones in extension. For instance, in the tests for initializeProvider we not only test that the provider is set but also that infuraIsBlocked or infuraIsUnblocked is emitted and that the network status is updated, etc.. So there are more tests we could bring over in this PR as it relates to Infura blocked/unblocked. That said, we could also cover that sort of thing in #1197. The tests you've added seem sufficient to prove that the new code is working as intended.

[Gudahtt]

Handling that as part of #1197 makes sense to me. I considered doing it here, but I wasn't sure if we wanted the final test suite to be organized that way. The way it's setup now (both in here and the extension) is... inconsistent and repetitive. We might want to factor our "lookupNetwork" behavioral tests into a function to more easily repeat them, or something like that.