preparing file service

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

backend/build.gradle.kts

@@ -16,6 +16,7 @@ dependencies{
     implementation(project(":contact"))
     implementation(project(":core"))
     implementation(project(":documents"))
+    implementation(project(":files"))
     implementation(project(":items"))
     implementation(project(":legacy"))
     implementation(project(":markdown"))