Forward person when a programming group is created with them

Further, we remove the "check invitation" button and extract some methods to our new ProgrammingGroups object in JavaScript.

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

app/assets/javascripts/channels/pg_matching_channel.js

@@ -0,0 +1,30 @@
+$(document).on('turbolinks:load', function () {
+
+    if ($.isController('programming_groups') && window.location.pathname.includes('programming_groups/new')) {
+        const matching_page = $('#matching');
+        const exercise_id = matching_page.data('exercise-id');
+
+        App.pg_matching = App.cable.subscriptions.create({
+            channel: "PgMatchingChannel", exercise_id: exercise_id
+        }, {
+            connected() {
+                // Called when the subscription is ready for use on the server
+            },
+
+            disconnected() {
+                // Called when the subscription has been terminated by the server
+            },
+
+            received(data) {
+                // Called when there's incoming data on the websocket for this channel
+                switch (data.action) {
+                    case 'invited':
+                        if (!ProgrammingGroups.is_other_user(data.user)) {
+                            window.location.reload();
+                        }
+                        break;
+                }
+            },
+        });
+    }
+});