Add an xb-workspaces-dev command

[TravisCarden]

This command performs some common setup tasks developers use when working with Workspaces and Workspaces Extras:

$ ddev xb-workspaces-dev --dry-run
This command will...
  1. Install the following modules:
     - Workspaces (workspaces)
     - Workspaces UI (workspaces_ui)
     - Workspaces Extras (wse)
     - Workspaces Config (wse_config)
  2. Perform the following configuration:
     - Use the simplified workspace switcher in the toolbar
     - Disable sub workspaces

It can be run on a fresh or existing environment, as long as ddev xb-setup has already been run.