Add server-specific member banners

[ToothyDev]

Summary

It isn't possible to access a member's server specific banner, if set

What is the feature request for?

The core library

The Problem

Currently, only Member.banner exists. This is different from avatars, where both Member.avatar and Member.display_avatar are implemented. This makes it impossible to access members' server-specific banners, as currently, Member.banner will always return their globally set banner

The Ideal Solution

Member.display_banner is added, making it possible to access members' server-specific banners if set

The Current Solution

No response

Additional Context

No response

[plun1331]

Someone else take care of this, I'm on vacation :p