Scanner must normalize new children names for cache diff

Since new children from the storage might contain NFD entries, these
must be normalized to NFC to be properly diff'ed with the cache
contents which is always NFC.

This fixes an issue where NFD entries would disappear from the cache
after rescannng for children.

lib/private/Files/Cache/Scanner.php

@@ -341,7 +341,7 @@ class Scanner extends BasicEmitter implements IScanner {
 			if (is_resource($dh)) {
 				while (($file = readdir($dh)) !== false) {
 					if (!Filesystem::isIgnoredDir($file)) {
-						$children[] = $file;
+						$children[] = trim(\OC\Files\Filesystem::normalizePath($file), '/');
 					}
 				}
 			}