feat: add worker node to the cluster

[dkeven]

two node-related commands are added:

• olares-cli node masterinfo for getting information about a target master node, and checks whether current node can be added to the cluster.
• olares-cli node add for adding current node to the Kubernetes cluster as a worker node.

both commands share a same set of options that specify how to access the master node by SSH:

option	explain	required	default
master-host	the IP address of the master node	true
master-node-name	the Kubernetes node name of the master node	false	false
master-ssh-user	the Linux user name to login to the master node by SSH	false	root
master-ssh-password	the password of the Linux user	true for non-root master-ssh-user
master-ssh-private-key-path	the private SSH key to authenticate as the Linux user	false	$HOME/.ssh/id_rsa
master-ssh-port	the listening port of the SSH service on the master node	false	22

some changes at the framework level is made, to make it possible to operate on two nodes simultaneously, in order to add worker node:

previously, in 7725447 and a550861:

a RemoteTask is made effectively the same as a LocalTask in that it does not use a SSH connection:

Installer/pkg/core/task/remote_task.go

Lines 164 to 182 in 0ef8cea

	func (t *RemoteTask) ConfigureSelfRuntime(runtime connector.Runtime, host connector.Host, index int) error {
	// var conn connector.Connection
	// var err error
	// if !host.GetMinikube() {
	// conn, err = runtime.GetConnector().Connect(host)
	// if err != nil {
	// return errors.Wrapf(err, "failed to connect to %s", host.GetAddress())
	// }
	// }
	r := &connector.Runner{
	Conn: nil,
	//Debug: runtime.Arg.Debug,
	Host: host,
	Index: index,
	}
	runtime.SetRunner(r)
	return nil
	}

and all remote commands (via SSH connection by runtime.GetRunner().Cmd()) are changed to run locally (by runtime.GetRunner().Host.Cmd())

these changes are partially reverted and partially merged into the original code, specifically, RemoteTask and LocalTask are made more interchangeable by:

• when initiating a RemoteTask, if the target host is not the local machine, a SSH connection is established, otherwise a nil connection is passed to the Runner, indicating it's running on a local machine
• when initiating a LocalTask, a real host is fetched from the runtime's host map first, instead of the current dummy localhost, to retain the host's roles
• when calling methods like runtime.GetRunner().Cmd(), the Runner's connection field is checked, if one exists, the SSH connection is used to execute the command, otherwise, the command is passed to Runner's host to execute locally.
• all runtime.GetRunner().Host.Cmd() is changed back to runtime.GetRunner().Cmd()
• when calling methods like runtime.GetRunner().SudoCmd(), the host's user is checked, a sudo prefix is added to the command only if the user is not root

some other module level changes are made to adjust the new cases for a worker node, when it needs to install JuiceFS based on a remote Redis server, and when the storage and K8s services need reconfiguration when its IP changes.

a new option --new-master-host is added to the change-ip command, to handle the case where a master node's IP address has changed, but the worker node has no way to automatically know it.