also changes the signature of AutoHandler to use client.Client because client.Reader was too narrow for the refactored implementation

* refactor(mgr) use booleans for controller flags

Change flags for managing controllers from a custom
enabled/auto/disabled type to booleans. By default, all controllers are
enabled. If a controller's enable flag is set to false, it is disabled.
Enabled controllers that have an auto loader are loaded if they are
enabled and their auto loader indicates they should load.

Remove the KongStateEnabled flag. This was a leftover from an earlier
design where the controller managed Kong state information via a special
Secret. It had no remaining associated code and was only present in
configuration.

Rename controller flags to reflect that they enable controllers.

Remove enablement status type, associated utility functions, and custom
flag handler.

* fix(test) only defer body close if exists

Move deferred body close checks after the error checkers. If an error is
present, no body exists, and the deferred attempt to close it segfaults.

Co-authored-by: Michał Flendrich <michal@flendrich.pro>