feat: allow adding custom attributes to conversations from the SDK (#6782)

* feat: add conversation attributes method to sdk and widget app

* feat: add endpoints to update custom attributes

* refactor: update SDK api

* feat: add api and actions for conversation updates

* fix: error message

* test: custom attributes on conversations controller

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Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

config/routes.rb

@@ -226,6 +226,8 @@ Rails.application.routes.draw do
         resources :messages, only: [:index, :create, :update]
         resources :conversations, only: [:index, :create] do
           collection do
+            post :destroy_custom_attributes
+            post :set_custom_attributes
             post :update_last_seen
             post :toggle_typing
             post :transcript