[Tech Debt] Replace all references to store.$plugin in navigation-guards/clusters.js

[codyrancher]

Replace all references to store.$plugin in navigation-guards/clusters.js. We really shouldn't be making references to the store in this way. We most likely don't want plugin to be a part of store and if we must access it it should at least be through a getter.

Unfortunately the initialization code has circular dependencies between creating the router and creating the store that will need to be untangled before this can be tackled.