assign container_project inverse_of values

when fetching container groups from a container_project, it was not assigning the reverse association
added `inverse_of` to get them assigned (and avoid N+1)

changed ext_management_system class to one that had the `container_projects` reference

app/models/container_project.rb

@@ -8,15 +8,15 @@ class ContainerProject < ApplicationRecord
  include TenantIdentityMixin
  include CustomActionsMixin
  include_concern 'Purging'
- belongs_to :ext_management_system, :foreign_key => "ems_id"
- has_many :container_groups, -> { active }
+ belongs_to :ext_management_system, :class_name => "ContainerManager", :foreign_key => "ems_id", :inverse_of => :container_projects
+ has_many :container_groups, -> { active }, :inverse_of => :container_project
  has_many :container_routes
  has_many :container_replicators
  has_many :container_services
  has_many :containers, :through => :container_groups
  has_many :container_images, -> { distinct }, :through => :container_groups
  has_many :container_nodes, -> { distinct }, :through => :container_groups
- has_many :container_quotas, -> { active }
+ has_many :container_quotas, -> { active }, :inverse_of => :container_project
  has_many :container_quota_scopes, :through => :container_quotas
  has_many :container_quota_items, :through => :container_quotas
  has_many :container_limits

spec/models/container_project_spec.rb

@@ -31,6 +31,9 @@
 
  groups = project.container_groups.to_a
  expect(groups).to match_array([group_active])
+ expect do
+ expect(groups.first.container_project).to eq(project)
+ end.not_to make_database_queries
  end
  end
 end