fix: account email validation during signup (#11307)

- Refactor email validation logic to be a service
- Use the service for both email/pass signup and Google SSO
- fix account email validation during signup
- Use `blocked_domain` setting for both email/pass signup and Google
Sign In [`BLOCKED_DOMAIN` via GlobalConfig]
- add specs for `account_builder`
- add specs for the new service

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>

app/services/account/sign_up_email_validation_service.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+class Account::SignUpEmailValidationService
+  include CustomExceptions::Account
+  attr_reader :email
+
+  def initialize(email)
+    @email = email
+  end
+
+  def perform
+    address = ValidEmail2::Address.new(email)
+
+    raise InvalidEmail.new({ valid: false, disposable: nil }) unless address.valid?
+
+    raise InvalidEmail.new({ domain_blocked: true }) if domain_blocked?
+
+    raise InvalidEmail.new({ valid: true, disposable: true }) if address.disposable?
+
+    true
+  end
+
+  private
+
+  def domain_blocked?
+    domain = email.split('@').last&.downcase
+    blocked_domains.any? { |blocked_domain| domain.match?(blocked_domain.downcase) }
+  end
+
+  def blocked_domains
+    domains = GlobalConfigService.load('BLOCKED_EMAIL_DOMAINS', '')
+    return [] if domains.blank?
+
+    domains.split("\n").map(&:strip)
+  end
+end