upgrades: add authorize.net integration.

Add integration for accepting payments with Authorize.net.

https://developer.authorize.net/hello_world.html

app/controllers/user_upgrades_controller.rb

@@ -4,7 +4,7 @@ class UserUpgradesController < ApplicationController
   respond_to :js, :html, :json, :xml
 
   def create
-    @user_upgrade = authorize UserUpgrade.create(recipient: recipient, purchaser: CurrentUser.user, status: "pending", upgrade_type: params[:upgrade_type])
+    @user_upgrade = authorize UserUpgrade.create(recipient: recipient, purchaser: CurrentUser.user, status: "pending", upgrade_type: params[:upgrade_type], payment_processor: params[:payment_processor])
     @country = params[:country] || CurrentUser.country || "US"
     @allow_promotion_codes = params[:promo].to_s.truthy?
     @checkout = @user_upgrade.create_checkout!(country: @country, allow_promotion_codes: @allow_promotion_codes)

app/controllers/webhooks_controller.rb

@@ -1,7 +1,8 @@
 # frozen_string_literal: true
 
 class WebhooksController < ApplicationController
-  skip_forgery_protection only: :receive
+  skip_forgery_protection only: [:receive, :authorize_net]
+
   rescue_with Stripe::SignatureVerificationError, status: 400
   rescue_with DiscordSlashCommand::WebhookVerificationError, status: 401
 
@@ -17,4 +18,9 @@ class WebhooksController < ApplicationController
       head 400
     end
   end
+
+  def authorize_net
+    PaymentTransaction::AuthorizeNet.receive_webhook(request)
+    head 200
+  end
 end