Remove deprecated modules

[taylortom]

Feature description

After a sensible amount of time we'll need the following repos deleted from here, and unpublished from npm:

• adapt-authoring-browserslist
• adapt-authoring-config
• adapt-authoring-defaultplugins
• adapt-authoring-errors
• adapt-authoring-lang
• adapt-authoring-logger
• adapt-authoring-sessions