Migrate AnomalyNotification to contributor

* Also, this commit aims to fix the (broken) anomaly notifications.

app/models/anomaly_notification.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class AnomalyNotification < ApplicationRecord
-  include Creation
+  include ContributorCreation
   belongs_to :exercise
   belongs_to :exercise_collection
 end

app/models/exercise.rb

@@ -14,6 +14,7 @@ class Exercise < ApplicationRecord
   belongs_to :execution_environment, optional: true
   has_many :submissions
 
+  has_many :anomaly_notifications, as: :contributor, dependent: :destroy
   has_and_belongs_to_many :proxy_exercises
   has_many :user_proxy_exercise_exercises
   has_many :exercise_collection_items, dependent: :delete_all
@@ -596,14 +597,14 @@ class Exercise < ApplicationRecord
     end
   end
 
-  def last_submission_per_user
+  def last_submission_per_contributor
     Submission.joins("JOIN (
           SELECT
               contributor_id,
               contributor_type,
-              first_value(id) OVER (PARTITION BY contributor_id ORDER BY created_at DESC) AS fv
+              first_value(id) OVER (PARTITION BY contributor_id, contributor_type ORDER BY created_at DESC) AS fv
           FROM submissions
-          WHERE exercise_id = #{id}
+          WHERE #{Submission.sanitize_sql(['exercise_id = ?', id])}
         ) AS t ON t.fv = submissions.id").distinct
   end
 

app/models/exercise_collection.rb

@@ -4,6 +4,7 @@ class ExerciseCollection < ApplicationRecord
   include Creation
   include TimeHelper
 
+  has_many :anomaly_notifications, dependent: :destroy
   has_many :exercise_collection_items, dependent: :delete_all
   alias items exercise_collection_items
   has_many :exercises, through: :exercise_collection_items, inverse_of: :exercise_collections

app/models/programming_group.rb

@@ -3,6 +3,7 @@
 class ProgrammingGroup < ApplicationRecord
   include Contributor
 
+  has_many :anomaly_notifications, as: :contributor, dependent: :destroy
   has_many :programming_group_memberships, dependent: :destroy
   has_many :external_users, through: :programming_group_memberships, source_type: 'ExternalUser', source: :user
   has_many :internal_users, through: :programming_group_memberships, source_type: 'InternalUser', source: :user

app/models/user.rb

@@ -6,6 +6,7 @@ class User < ApplicationRecord
   attr_reader :current_study_group_id
 
   belongs_to :consumer
+  has_many :anomaly_notifications, as: :contributor, dependent: :destroy
   has_many :authentication_token, dependent: :destroy
   has_many :study_group_memberships, as: :user
   has_many :study_groups, through: :study_group_memberships, as: :user