feat(library): add source chips to game library

Chips show only when the user has 2 or more sources.
A selected source the user lacks stays visible, so it can be cleared.

public/i18n/de.json

@@ -256,6 +256,8 @@
     }
   },
   "LIBRARY": {
+    "SOURCE_LABEL": "Quelle",
+    "SOURCE": { "STEAM": "Steam", "PSN": "PlayStation", "MANUAL": "Manuell" },
     "TITLE": "Spielebibliothek",
     "LOADING": "Lade Spiele …",
     "EMPTY": "Noch keine Spiele. Synchronisiere deine Steam-Bibliothek oder füge ein Spiel hinzu.",