Update namespacing & naming

app/models/account.rb

@@ -1,5 +1,5 @@
 class Account < ApplicationRecord
-  include Account::Storage, Entropic, MultiTenant, Seedeable
+  include Account::Storage, Entropic, MultiTenantable, Seedeable
 
   has_one :join_code
   has_many :users, dependent: :destroy

app/models/account/multi_tenantable.rb

@@ -1,4 +1,4 @@
-module MultiTenant
+module Account::MultiTenantable
   extend ActiveSupport::Concern
 
   included do

test/models/account/multi_tenantable_test.rb

@@ -1,6 +1,6 @@
 require "test_helper"
 
-class MultiTenantTest < ActiveSupport::TestCase
+class Account::MultiTenantableTest < ActiveSupport::TestCase
   test "accepting_signups? is true when multi_tenant is enabled" do
     with_multi_tenant_mode(true) do
       assert Account.accepting_signups?