It was being recalculated repeatedly.
This memoizes it, although it still re-calculates occasionally despite none of the source arrays changed. I think it is due to the state change in the Preference Sync.
Note: input selectors to `createSelector` needs to be extractions-only (i.e. must not have transformations). I think most of our `makeSelect*` selectors violate this and broke memoization.
* initial support for block/mute
* hide blocked + muted content everywhere
* add info message for blocked/muted characteristics
* sort blocked list by most recent block first
* add 'blocked' message on channel page for channels that you have blocked
* cleanup
* delete unused files
* always pass mute/block list to claim_search on homepage
* PR cleanup
