Ruby: add databaseMetadata relation to dbscheme

This is required for overlay support.

config/dbscheme-fragments.json

@@ -11,6 +11,7 @@
     "/*- Diagnostic messages -*/",
     "/*- Diagnostic messages: severity -*/",
     "/*- Source location prefix -*/",
+    "/*- Database metadata -*/",
     "/*- Lines of code -*/",
     "/*- Configuration files with key value pairs -*/",
     "/*- YAML -*/",
@@ -31,4 +32,4 @@
     "/*- Python dbscheme -*/",
     "/*- Empty location -*/"
   ]
-}
+}