Go-github: feat: add support for affiliation in the Repositories.ListCollaborators opts

[dnwe]

As per the apidoc, at some point a request option was added for filtering the returned collaborators by affiliation. It would be useful if that was exposed as part of a custom ListCollaboratorOptions struct

[dmitshur]

This will have to be a breaking API change. But it's warranted.

ListCollaborators method signature currently accepts a plain opt *ListOptions. We'll need to give it a custom ListCollaboratorsOptions which embeds ListOptions and has the new affiliation parameter.

[sahildua2305]

I'll take this up, @shurcooL. Feel free to assign it to me.

[elliott-beach]

Is this issue being worked on? If not, could it be assigned to me?

[sahildua2305]

@e-beach thanks for showing interest in taking over this. This is yours. 👍

@gmlewis please re-assign this, I couldn't find time to work on this.