Webdav: fully implements the controller and response

The controller is tested from real request scraped from apache mod_dav implementation. The requests were scraped using a wireshark-like tool. Those requests have been adapted to suit to our xml.

src/Bundle/ChillDocStoreBundle/Service/StoredObjectManagerInterface.php

@@ -18,6 +18,8 @@ interface StoredObjectManagerInterface
 {
     public function getLastModified(StoredObject $document): \DateTimeInterface;
 
+    public function getContentLength(StoredObject $document): int;
+
     /**
      * Get the content of a StoredObject.
      *
@@ -39,5 +41,7 @@ interface StoredObjectManagerInterface
      */
     public function write(StoredObject $document, string $clearContent): void;
 
+    public function etag(StoredObject $document): string;
+
     public function clearCache(): void;
 }