Add failover support to RpcService

[mcmire]

Explanation

Add a new failoverService option to RpcService. This allows consumers to forward the request to another RPC service in the event that an RPC endpoint is proven to be unreliable (i.e. after attempting the request 5 times, the endpoint is unreachable, returns a a non-200 response, or returns a response that is not JSON-decodable).

References

Closes #4992.

Changelog

(N/A; RpcService is not public yet so no changelog updates)

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've highlighted breaking changes using the "BREAKING" category above as appropriate
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes

[mcmire]

@metamaskbot publish-previews

[github-actions]

Preview builds have been published. See these instructions for more information about preview builds.

Expand for full list of packages and versions.

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[mikesposito]

LGTM!