Support for wiki attachments

## Description

It would be great to manage wikipage attachments in a similar fashion 

## Use cases

Migrating / syncing wiki pages 

## Proposed solution

Extending the wikipage class with  a `list_attachments`  method 

## Alternatives

Right now, it seems to me i have to parse the HTML of a wikipage and find the URL's of the attachments to get them using requests .  
