Improve CLI Discovery output (#583)

- Show discovery results for unsupported devices and devices that fail to authenticate.
- Rename `--show-unsupported` to `--verbose`.
- Remove separate `--timeout` parameter from cli discovery so it's not confused with `--timeout` now added to cli command.
- Add tests.

kasa/exceptions.py

@@ -9,6 +9,10 @@ class SmartDeviceException(Exception):
 class UnsupportedDeviceException(SmartDeviceException):
     """Exception for trying to connect to unsupported devices."""
 
+    def __init__(self, *args, discovery_result=None):
+        self.discovery_result = discovery_result
+        super().__init__(args)
+
 
 class AuthenticationException(SmartDeviceException):
     """Base exception for device authentication errors."""