Add support to choose the sheet within google spreadsheets

app/models/form.rb

@@ -38,9 +38,10 @@ class Form < ApplicationRecord
     backend_name == 'airtable'
   end
 
-  def google
-    backend_name == 'google'
+  def google?
+    backend_name == 'google_sheets'
   end
+  def google; google?; end # TODO: remove this alias
 
   def backend
     @backend ||= SpreadsheetBackends.const_get(backend_name.camelize).new(self)