Feature: Feature flags on account (#814) (#815)

* Feature: Feature flags on account (#814)
* Added the new column on account model for managing feature flags
* Added the inbound email flag
* Locked the settings of this eature in account settings based on this
* Encapsulated the feature flaging as a concern. With this, we can re-use the same concern if we introduce this in other models like user or inbox or so.
* Added the features in the account api

* Changed Rails/FilePath style - rubocop issue

* Revert "Changed Rails/FilePath style - rubocop issue"

This reverts commit 3a42d3b9c9b3a2fde8bc7256fd704b6fcaf54040.

* Disabling rubocop on codeclimate as we already have this in CICD

app/models/account.rb

@@ -4,6 +4,7 @@
 #
 #  id             :integer          not null, primary key
 #  domain         :string(100)
+#  feature_flags  :integer          default(0), not null
 #  locale         :integer          default("en")
 #  name           :string           not null
 #  settings_flags :integer          default(0), not null
@@ -18,6 +19,7 @@ class Account < ApplicationRecord
 
   include Events::Types
   include Reportable
+  include Features
 
   DEFAULT_QUERY_SETTING = {
     flag_query_mode: :bit_operator