feat(notif): add Pushover sound options (#2403)

Co-authored-by: Danshil Kokil Mungur <me@danshilm.com>

server/interfaces/api/userSettingsInterfaces.ts

@@ -28,6 +28,7 @@ export interface UserSettingsNotificationsResponse {
   pushbulletAccessToken?: string;
   pushoverApplicationToken?: string;
   pushoverUserKey?: string;
+  pushoverSound?: string;
   telegramEnabled?: boolean;
   telegramBotUsername?: string;
   telegramChatId?: string;