Authentication support

[philrz]

Right now the plugin only supports access to an unauthenticated Zed service such as a zed serve started with defaults or the one that runs on localhost behind Zui. However, a Zed service may be configured to require authentication, so the plugin should be enhanced to work with this. Preliminary research has indicated that the approaches for auth currently available in Zed would not be workable with the plugin, so additional work will be required on the Zed side.