Refactor Blubber using vue, closes #1695

app/controllers/blubber.php

app/controllers/course/messenger.php

app/views/blubber/dialog.php

app/views/blubber/index.php

lib/classes/JsonApi/JsonApiIntegration/QueryChecker.php

lib/classes/JsonApi/RouteMap.php

lib/classes/JsonApi/Routes/Blubber/Authority.php

lib/classes/JsonApi/Routes/Blubber/CommentsByThreadIndex.php

lib/classes/JsonApi/Routes/Blubber/CommentsCreate.php

lib/classes/JsonApi/Routes/Blubber/Rel/DefaultThread.php

lib/classes/JsonApi/Routes/Blubber/SortTrait.php

lib/classes/JsonApi/Routes/Blubber/ThreadsUpdate.php

lib/classes/JsonApi/Schemas/BlubberComment.php

lib/classes/JsonApi/Schemas/BlubberThread.php

lib/classes/JsonApi/Schemas/User.php

lib/classes/sidebar/BlubberThreadsWidget.php

lib/models/BlubberThread.php

resources/assets/javascripts/chunk-loader.js

resources/assets/javascripts/entry-base.js

resources/assets/javascripts/init.js