feature: add launch method to Node class (#849)

* feature: add launch method to Node class

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: vicu <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: 3 people

jenkinsapi/node.py

@@ -269,6 +269,27 @@ def set_offline(self, message="requested from jenkinsapi") -> None:
                     % (data["offline"], data["temporarilyOffline"])
                 )
 
+    def launch(self) -> None:
+        """
+        Tries to launch a connection with the slave if it is currently
+        disconnected. Because launching a connection with the slave does not
+        mean it is online (a slave can be launched, but set offline), this
+        function does not check if the launch was successful.
+        """
+        if not self._data["launchSupported"]:
+            raise AssertionError("The node does not support manually launch.")
+
+        if not self._data["manualLaunchAllowed"]:
+            raise AssertionError(
+                "It is not allowed to manually launch this node."
+            )
+
+        url = self.baseurl + "/launchSlaveAgent"
+        html_result = self.jenkins.requester.post_and_confirm_status(
+            url, data={}
+        )
+        log.debug(html_result)
+
     def toggle_temporarily_offline(
         self, message="requested from jenkinsapi"
     ) -> None: