Fullscreen keybind (#961)

# Added
- Added: Added 'f' as keybind to toggle fullscreen on manga and book readers.

UI/Web/src/app/book-reader/book-reader/book-reader.component.ts

@@ -494,6 +494,8 @@ export class BookReaderComponent implements OnInit, AfterViewInit, OnDestroy {
       event.preventDefault(); 
     } else if (event.key === KEY_CODES.G) {
       this.goToPage();
+    } else if (event.key === KEY_CODES.F) {
+      this.toggleFullscreen()
     }
   }