Account:: namespace simplifications and cleanup (#2110)

* Flatten Holding model

* Flatten balance model

* Entries domain renames

* Fix valuations reference

* Fix trades stream

* Fix brakeman warnings

* Fix tests

* Replace existing entryable type references in DB

test/models/family/auto_transfer_matchable_test.rb

@@ -1,7 +1,7 @@
 require "test_helper"
 
 class Family::AutoTransferMatchableTest < ActiveSupport::TestCase
-  include Account::EntriesTestHelper
+  include EntriesTestHelper
 
   setup do
     @family = families(:dylan_family)