Add custom emoji size recording and publish api

app/controllers/admin/custom_emojis_controller.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'fastimage'
+
 module Admin
   class CustomEmojisController < BaseController
     def index
@@ -18,7 +20,11 @@ module Admin
     def create
       authorize :custom_emoji, :create?
 
+      image_size = FastImage.size(params[:custom_emoji][:image])
+
       @custom_emoji = CustomEmoji.new(resource_params)
+      @custom_emoji.image_width = image_size[0]
+      @custom_emoji.image_height = image_size[1]
 
       if @custom_emoji.save
         log_action :create, @custom_emoji