Make getBaseDomain use LRU cache

[bbondy]

@diracdeltas mentions this function is slow and we call it during filtering so we should be using an LRU cache for the lookups.

[bbondy]

We use it already in other parts of the code like here:
app/trackingProtection.js:const LRUCache = require('lru_cache/core').LRUCache

[david-gang]

Hi @bbondy ,

It is not clear to me what should be done.
Should the line 198 in the commit 144f786
changed from !refererExceptions.includes(parsedUrl.hostname) to !refererExceptions.includes(getBaseName(parsedUrl.hostname)) and then in getBasName we will implement the lru cache?