Check if octoprint.server.util.(loginFromApiKeyRequestHandler|loginFromAuthorizationHeaderRequestHandler) are still needed

[foosel]

Problem

octoprint.server.util.(loginFromApiKeyRequestHandler|loginFromAuthorizationHeaderRequestHandler) currently duplicate some code and are likely superseded by the switch to using a request loader in flask_login now in the shape of octoprint.server.load_user_from_request.

Solution

Evaluate whether these methods and their dependencies can indeed be removed, and if so do that.

[foosel]

That's now cleaned up and hopefully still works as before.