feat: Add a sort option for conversations waiting for a reply from an agent (#7364)

db/migrate/20230620212340_add_waiting_since_to_conversations.rb

@@ -0,0 +1,6 @@
+class AddWaitingSinceToConversations < ActiveRecord::Migration[7.0]
+  def change
+    add_column :conversations, :waiting_since, :datetime
+    add_index :conversations, :waiting_since
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.0].define(version: 2023_06_20_132319) do
+ActiveRecord::Schema[7.0].define(version: 2023_06_20_212340) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_stat_statements"
   enable_extension "pg_trgm"
@@ -449,6 +449,7 @@ ActiveRecord::Schema[7.0].define(version: 2023_06_20_132319) do
     t.datetime "first_reply_created_at", precision: nil
     t.integer "priority"
     t.bigint "sla_policy_id"
+    t.datetime "waiting_since"
     t.index ["account_id", "display_id"], name: "index_conversations_on_account_id_and_display_id", unique: true
     t.index ["account_id", "id"], name: "index_conversations_on_id_and_account_id"
     t.index ["account_id", "inbox_id", "status", "assignee_id"], name: "conv_acid_inbid_stat_asgnid_idx"
@@ -465,6 +466,7 @@ ActiveRecord::Schema[7.0].define(version: 2023_06_20_132319) do
     t.index ["status", "priority"], name: "index_conversations_on_status_and_priority"
     t.index ["team_id"], name: "index_conversations_on_team_id"
     t.index ["uuid"], name: "index_conversations_on_uuid", unique: true
+    t.index ["waiting_since"], name: "index_conversations_on_waiting_since"
   end
 
   create_table "csat_survey_responses", force: :cascade do |t|