Allow servers to change all default emoji's with their own set

They'll on it's best resemble the default emoji names, all emoji's will just look different for the time the server is boosted to a certain level.

It doesn't have to be complete and users should be able to turn the feature off for accessibility.

Every server can just have 1 pack enabled, so if you update it, no old versions exist: you have to update the pack as 1 zip file and every file that's not a default emoji will be thrown out.

Additionally, on a lower boost level/with nitro, servers and users could choose between the ones available on emojipedia and for feedback about using device/browser stock emoji, go here: https://support.discord.com/hc/en-us/community/posts/360051142793-Emoji-style-change-option