Enable interventions for ProgrammingGroups and add indices

app/models/intervention.rb

@@ -2,12 +2,18 @@
 
 class Intervention < ApplicationRecord
   has_many :user_exercise_interventions
-  has_many :users, through: :user_exercise_interventions, source_type: 'ExternalUser'
+  has_many :external_users, through: :user_exercise_interventions, source: :contributor, source_type: 'ExternalUser'
+  has_many :internal_users, through: :user_exercise_interventions, source: :contributor, source_type: 'InternalUser'
+  has_many :programming_groups, through: :user_exercise_interventions, source: :contributor, source_type: 'ProgrammingGroup'
 
   def to_s
     name
   end
 
+  def contributors
+    @contributors ||= internal_users.distinct + external_users.distinct + programming_groups.distinct
+  end
+
   def self.create_default_interventions
     %w[BreakIntervention QuestionIntervention].each do |name|
       Intervention.find_or_create_by(name:)

app/models/user.rb

@@ -18,7 +18,7 @@ class User < ApplicationRecord
   has_many :submissions, as: :contributor
   has_many :participations, through: :submissions, source: :exercise, as: :user
   has_many :user_proxy_exercise_exercises, as: :user
-  has_many :user_exercise_interventions, as: :user
+  has_many :user_exercise_interventions, as: :contributor
   has_many :testruns, as: :user
   has_many :interventions, through: :user_exercise_interventions
   has_many :remote_evaluation_mappings, as: :user

app/models/user_exercise_intervention.rb

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