refactor: adjust to unexposed searchBySystemTag

- in this backport we have to drop the breaking addition in
  \OCP\Files\Folder
- this requires adjustments in check for the existance of the method but
  also in testing
- another change in \OCP\SystemTag\ISystemTagManager can be applied as
  this interface is not implemented elsewhere

Signed-off-by: Arthur Schiwon <blizzz@arthur-schiwon.de>

Author: blizzz

apps/dav/lib/Connector/Sabre/FilesReportPlugin.php

@@ -336,7 +336,7 @@ protected function processFilterRulesForFileNodes(array $filterRules, ?int $limi
 
 		// type check to ensure searchBySystemTag is available, it is not
 		// exposed in API yet
-		if (!empty($systemTagIds)) {
+		if (!empty($systemTagIds) && method_exists($this->userFolder, 'searchBySystemTag')) {
 			$tags = $this->tagManager->getTagsByIds($systemTagIds, $this->userSession->getUser());
 
 			// For we run DB queries per tag and require intersection, we cannot apply limit and offset for DB queries on multi tag search.

apps/dav/tests/unit/Connector/Sabre/FilesReportPluginTest.php

@@ -114,6 +114,8 @@ protected function setUp(): void {
 
 		$this->userFolder = $this->getMockBuilder(Folder::class)
 			->disableOriginalConstructor()
+			->addMethods(['searchBySystemTag'])
+			->onlyMethods(get_class_methods(Folder::class))
 			->getMock();
 
 		$this->previewManager = $this->getMockBuilder(IPreview::class)

lib/public/SystemTag/ISystemTagManager.php

@@ -46,7 +46,7 @@ interface ISystemTagManager {
 	 * @throws TagNotFoundException if at least one given tag ids did no exist
 	 * 			The message contains a json_encoded array of the ids that could not be found
 	 *
-	 * @since 9.0.0, optional parameter $user added in 28.0.0
+	 * @since 9.0.0, optional parameter $user added in 27.0.1
 	 */
 	public function getTagsByIds($tagIds, ?IUser $user = null): array;