Return preset from Member::find_guild if possible
Return preset from Member::find_guild if possible

If a value is present for `Member::guild_id` when calling
`Member::find_guild`, return that value instead of searching the cache.

This can potentially save a large amount of calculations and time.

Roughsketch/serenity,Lakelezz/serenity,zeyla/serenity,acdenisSK/serenity,Flat/serenity,zeyla/serenity.rs,eLunate/serenity