chore: Introduce enterprise edition license (#3209)

- Initialize an "enterprise" folder that is copyrighted.
- You can remove this folder and the system will continue functioning normally, in case you want a purely MIT licensed product.
- Enable limit on the number of user accounts in enterprise code.
- Use enterprise edition injector methods (inspired from Gitlab).
- SaaS software would run enterprise edition software always.

Co-authored-by: Pranav Raj S <pranav@chatwoot.com>

app/models/account.rb

@@ -6,6 +6,7 @@
 #  auto_resolve_duration :integer
 #  domain                :string(100)
 #  feature_flags         :integer          default(0), not null
+#  limits                :jsonb
 #  locale                :integer          default("en")
 #  name                  :string           not null
 #  settings_flags        :integer          default(0), not null
@@ -19,6 +20,7 @@ class Account < ApplicationRecord
   include FlagShihTzu
   include Reportable
   include Featurable
+  prepend_mod_with('Account')
 
   DEFAULT_QUERY_SETTING = {
     flag_query_mode: :bit_operator,
@@ -107,6 +109,13 @@ class Account < ApplicationRecord
     super || GlobalConfig.get('MAILER_SUPPORT_EMAIL')['MAILER_SUPPORT_EMAIL'] || ENV.fetch('MAILER_SENDER_EMAIL', 'Chatwoot <accounts@chatwoot.com>')
   end
 
+  def usage_limits
+    {
+      agents: ChatwootApp.max_limit,
+      inboxes: ChatwootApp.max_limit
+    }
+  end
+
   private
 
   def notify_creation