Allow user to add buy and sell trade transactions for investment accounts (#1066)

* Consolidate modal form structure into partial + helper

* Scaffold out trade transaction form

* Normalize translations

* Add buy and sell trade form with tests

* Move entryable lists to dedicated controllers

* Delegate entry group contents rendering

* More cleanup

* Extract transaction and valuation update logic from entries controller

* Delegate edit and show actions to entryables

* Trade builder

* Update paths for transaction updates

test/support/account/entries_test_helper.rb

@@ -34,7 +34,8 @@ module Account::EntriesTestHelper
     trade = Account::Trade.new \
       qty: qty,
       security: security,
-      price: trade_price
+      price:    trade_price,
+      currency: "USD"
 
     account.entries.create! \
       name: "Trade",