DEV: Replace custom Onebox blank implementation with ActiveSupport (#23827)

We have a custom implementation of #blank? in our Onebox helpers. This is likely a legacy from when Onebox was a standalone gem. This change replaces all usages with respective incarnations of #blank?, #present?, and #presence from ActiveSupport. It changes a bunch of "unless blank" to "if present" as well.

lib/onebox/helpers.rb

@@ -165,9 +165,7 @@ module Onebox
         end
 
         http.request_head([uri.path, uri.query].join("?")) do |response|
-          code = response.code.to_i
-          return nil unless code === 200 || Onebox::Helpers.blank?(response.content_length)
-          return response.content_length
+          return response.code.to_i == 200 ? response.content_length.presence : nil
         end
       end
     end
@@ -190,27 +188,17 @@ module Onebox
       "<div style=\"background:transparent;position:relative;width:#{width}px;height:#{height}px;top:#{height}px;margin-top:-#{height}px;\" onClick=\"style.pointerEvents='none'\"></div>"
     end
 
-    def self.blank?(value)
-      if value.nil?
-        true
-      elsif String === value
-        value.empty? || !(/[[:^space:]]/ === value)
-      else
-        value.respond_to?(:empty?) ? !!value.empty? : !value
-      end
-    end
-
     def self.truncate(string, length = 50)
       return string if string.nil?
       string.size > length ? string[0...(string.rindex(" ", length) || length)] + "..." : string
     end
 
     def self.get(meta, attr)
-      (meta && !blank?(meta[attr])) ? sanitize(meta[attr]) : nil
+      (meta && meta[attr].present?) ? sanitize(meta[attr]) : nil
     end
 
     def self.sanitize(value, length = 50)
-      return nil if blank?(value)
+      return nil if value.blank?
       Sanitize.fragment(value).strip
     end