adding Lab6 Notifcations lab

Labs/Lab6_NotificationsLab/.gitignore

Labs/Lab6_NotificationsLab/Lab-Notifications.docx

Labs/Lab6_NotificationsLab/Lab-Notifications.pdf

Labs/Lab6_NotificationsLab/Notification_Lab_Video.webm

Labs/Lab6_NotificationsLab/app/build.gradle

Labs/Lab6_NotificationsLab/app/lint.xml

...st/java/course/labs/notificationslab/tests/NewFeedTest.kt

.../labs/notificationslab/tests/OldFeedNoNotificationTest.kt

...abs/notificationslab/tests/OldFeedWithNotificationTest.kt

.../Lab6_NotificationsLab/app/src/androidTest/res/.gitignore

Labs/Lab6_NotificationsLab/app/src/main/AndroidManifest.xml

...n/java/course/labs/notificationslab/CoroutineAsyncTask.kt

.../course/labs/notificationslab/DownloadFinishedListener.kt

...va/course/labs/notificationslab/DownloaderTaskFragment.kt

...rc/main/java/course/labs/notificationslab/FeedFragment.kt

...ain/java/course/labs/notificationslab/FeedFragmentData.kt

...main/java/course/labs/notificationslab/FriendsFragment.kt

...rc/main/java/course/labs/notificationslab/MainActivity.kt

...java/course/labs/notificationslab/TestFrontEndActivity.kt

...otificationsLab/app/src/main/res/layout/activity_main.xml