Transaction transfers, payments, and matching (#883)

* Add transfer model and clean up family snapshot fixtures

* Ignore transfers in income and expense snapshots

* Add transfer validations

* Implement basic transfer matching UI

* Fix merge conflicts

* Add missing translations

* Tweak selection states for transfer types

* Add missing i18n translation

config/routes.rb

@@ -46,6 +46,8 @@ Rails.application.routes.draw do
       post "bulk_delete"
       get "bulk_edit"
       post "bulk_update"
+      post "mark_transfers"
+      post "unmark_transfers"
 
       scope module: :transactions, as: :transaction do
         resources :rows, only: %i[ show update ]
@@ -63,6 +65,8 @@ Rails.application.routes.draw do
     end
   end
 
+  resources :transfers, only: %i[ new create destroy ]
+
   resources :accounts, shallow: true do
     get :summary, on: :collection
     get :list, on: :collection