feat(Guild): nsfw guilds (#5525)

Co-authored-by: Advaith <advaithj1@gmail.com>

typings/index.d.ts

@@ -641,6 +641,7 @@ declare module 'discord.js' {
     public mfaLevel: number;
     public name: string;
     public readonly nameAcronym: string;
+    public nsfw: boolean;
     public ownerID: Snowflake;
     public readonly partnered: boolean;
     public preferredLocale: string;