Refactor JWT to use around_action when needed instead of middleware used with every request

[nelsonwittwer]

Overview/summary

We currently use a JWT middleware to parse the JWT for every request that is made to a rails app that uses this gem. For actions that don't need to make API calls to Shopify we are still spending time logging and trying to parse a token that doesn't exist. For applications that have a large amount of traffic, this inefficiency adds up.

We should explore moving that logic to our controller concerns as part of a around_action or before_action filter so we only parse JWT when we know it'll be there.