Retrieve and cache subreddit toolbox settings

[Venefilyn]

We should retrieve and cache subreddit toolbox config for the same duration as toolbox caches it. This can be stored in Vuex state under some subreddits_config object

The main question now is: how do we retrieve the data in the simplest and most reliable way?

We might be able to utilize async Vuex getters that fetch the data either from cache or Reddit. But getters might not be able to dispatch actions or commit mutations.. if so we need to do some sort of check somewhere

[Venefilyn]

Since this will be stored in Vuex, this might be the best approach https://github.com/superwf/vuex-cache