Redefine MiqGroup #settings and #settings=

This commit ensures that #settings returns the same object that
exists in the object.

This ensures that calls like the following will work as expected:

group.settings[:a] = 1

Previously, #settings returned the duplicate object created by
Hash#with_indifferent_access

https://bugzilla.redhat.com/show_bug.cgi?id=1516793

app/models/miq_group.rb

@@ -45,7 +45,16 @@ def name
  end
 
  def settings
- super && super.with_indifferent_access
+ current = super
+ return if current.nil?
+
+ self.settings = current.with_indifferent_access
+ super
+ end
+
+ def settings=(new_settings)
+ indifferent_settings = new_settings.try(:with_indifferent_access)
+ super(indifferent_settings)
  end
 
  def self.with_allowed_roles_for(user_or_group)