feat: Business hour Inbox APIs (#1821)

* feat: Business hour Inbox APIs

db/migrate/20210222131048_change_working_hours_to_zero.rb

@@ -0,0 +1,11 @@
+class ChangeWorkingHoursToZero < ActiveRecord::Migration[6.0]
+  # rubocop:disable Rails/SkipsModelValidations
+  def up
+    WorkingHour.where(day_of_week: 7).update_all(day_of_week: 0)
+  end
+
+  def down
+    WorkingHour.where(day_of_week: 0).update_all(day_of_week: 7)
+  end
+  # rubocop:enable Rails/SkipsModelValidations
+end

db/migrate/20210222131155_switch_time_zone_from_account_to_inbox.rb

@@ -0,0 +1,6 @@
+class SwitchTimeZoneFromAccountToInbox < ActiveRecord::Migration[6.0]
+  def change
+    remove_column :accounts, :timezone, :string, default: 'UTC'
+    add_column :inboxes, :timezone, :string, default: 'UTC'
+  end
+end