Merge pull request #19890 from nextcloud/enh/comments-reference-id

Add optional comments reference_id

diff --cc apps/dav/tests/unit/Comments/CommentsNodeTest.php
Simple merge

diff --cc core/Application.php
Simple merge

diff --cc core/Command/Db/AddMissingIndices.php
Simple merge

diff --cc lib/composer/composer/autoload_classmap.php
Simple merge

diff --cc lib/composer/composer/autoload_static.php
Simple merge

diff --cc lib/public/IDBConnection.php
Simple merge