add level and exp to member class

[Meff1u]

e.g. :

const member = await client.members.fetch(serverid, memberid);
console.log(member.level, member.xp)

and it will return actual level and xp for guild.

[zaida04]

This is a limitation of the Guilded API. XP data is not actively returned by API routes, though there are some workarounds like using the setXp method with 0 xp which will return their current xp.