Uses the new features added to the bearer_authorization_header while dropping basic authentication support to simplify the creation of bearer authorization headers for API tests.
as discussed in [Issue #4509](https://wiki.openstreetmap.org/w/index.php?title=Messaging_API_proposal) and documented in [Messaging API reference](https://wiki.openstreetmap.org/w/index.php?title=Messaging_API_proposal)