feat: Add CSAT response APIs (#2503)

Co-authored-by: Pranav Raj S <pranav@chatwoot.com>

app/models/contact.rb

@@ -39,6 +39,7 @@ class Contact < ApplicationRecord
   belongs_to :account
   has_many :conversations, dependent: :destroy
   has_many :contact_inboxes, dependent: :destroy
+  has_many :csat_survey_responses, dependent: :destroy
   has_many :inboxes, through: :contact_inboxes
   has_many :messages, as: :sender, dependent: :destroy
   has_many :notes, dependent: :destroy