Replace the `VAGRANT_ALLOW_PARAM_AUTH_TOKEN` environment variable
with `VAGRANT_SERVER_ACCESS_TOKEN_BY_URL` and update the behavior
when the environment variable is set to add the access token as
a query parameter and disable the addition of the authentication
header.
Fixes #12080
Vagrant Core Plugins
These are plugins that ship with Vagrant. Vagrant core uses its own plugin system to power a lot of the core pieces that ship with Vagrant. Each plugin will have its own README which explains its specific role.