Add waiting room to create programming groups (#1919)

Co-authored-by: Sebastian Serth <Sebastian.Serth@hpi.de>

app/controllers/programming_groups_controller.rb

@@ -53,6 +53,9 @@ class ProgrammingGroupsController < ApplicationController
         ActionCable.server.broadcast("pg_matching_channel_exercise_#{@exercise.id}", message)
       end
 
+      # Check if the user was waiting for a programming group match and update the status
+      current_user.pair_programming_waiting_users&.find_by(exercise: @exercise)&.update(status: :created_pg, programming_group: @programming_group)
+
       # Just set the programming group id in the session for the creator of the group, so that the user can be redirected.
       session[:pg_id] = @programming_group.id