FIX: Store query groups in a temp table when fixing ids. (#68)

Reintroduces the migration removed in `cdfc5d4`, and fixes it to work with `query_groups`. Since the code is fairly complex, I moved into a rake task so it can be tested and make sure it works.

db/migrate/20200902225712_fix_query_ids.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class FixQueryIds < ActiveRecord::Migration[6.0]
+  def up
+    Rake::Task['data_explorer:fix_query_ids'].invoke
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end