fix!: reboot_host instead of reboot; drop run_device_action (0.2.0)

The gateway had reboot(), but the contract (HostRebootMixin) and the
application look for reboot_host(), so the gateway could not be
restarted from it. reboot_host() returns None and raises when the
gateway refuses, as the contract says.

run_device_action dispatched reboot, restart_wifi[:band] and
get_diagnostics by string, with a result shape other than its
contract's. restart_wifi(band) and get_diagnostics() are methods now;
napalm-device-types deprecates run_device_action.

BREAKING CHANGE: reboot() and run_device_action are removed.

Closes #5. Part of #6.

tests/test_zyxel.py

@@ -1,6 +1,7 @@
 import json
 from unittest.mock import MagicMock, patch
 
+import pytest
 import requests
 
 from napalm.base.exceptions import ConnectionException
@@ -285,16 +286,20 @@ class TestZyxelVMGDriver:
         self._setup_mocked_http()
         assert self.driver.get_arp_table() == []
 
-    def test_reboot(self):
-        self._setup_mocked_http()
-        result = self.driver.run_device_action("reboot")
-        assert result["action"] == "reboot"
+    def test_reboot_host_is_the_contract_the_application_calls(self):
+        """It was reboot(), which nothing looks for: the gateway could not be
+        restarted from the application (#5)."""
+        self.driver._dal_query = lambda name, data: {"result": "ZCFG_SUCCESS"}
+        assert self.driver.reboot_host() is None
 
-    def test_run_device_action_unknown(self):
-        self._setup_mocked_http()
-        result = self.driver.run_device_action("foobar")
-        assert result["success"] is False
-        assert "Unknown" in result["message"]
+    def test_a_refused_reboot_raises(self):
+        self.driver._dal_query = lambda name, data: {"result": "ZCFG_FAIL"}
+        with pytest.raises(RuntimeError):
+            self.driver.reboot_host()
+
+    def test_run_device_action_and_reboot_are_gone(self):
+        assert not hasattr(type(self.driver), "run_device_action")
+        assert not hasattr(type(self.driver), "reboot")
 
     def test_load_replace_candidate_raises(self):
         self._setup_mocked_http()