Use http POST on rules acceptance button during registration (#39345)

app/controllers/auth/acceptances_controller.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class Auth::AcceptancesController < ApplicationController
+  def create
+    redirect_to new_user_registration_path(registration_params)
+  end
+
+  private
+
+  def registration_params
+    params.permit(:accept, :invite_code).compact_blank
+  end
+end

app/views/auth/registrations/rules.html.haml

@@ -4,7 +4,7 @@
 - content_for :header_tags do
   = render partial: 'shared/og', locals: { description: description_for_sign_up(@invite) }
 
-= form_with class: :simple_form, method: :get, url: new_user_registration_path do |form|
+= form_with class: :simple_form, url: auth_acceptance_path do |form|
   = render 'auth/shared/progress', stage: 'rules'
 
   - if @invite.present? && @invite.autofollow?