Simplify applying the generated configuration

[mirceanton]

Currently, the workflow to bootstrap a Talos cluster using talhelper is to generate the per-node configuration files using talhlper genconfig and then manually writing the talosctl apply commands, pointing it to the right config file and the right node.

Given that the talconfig.yaml already contains all the required information in order to apply the config as well, I think that talhelper should have a subcommand which simplifies this process.

This could either be a command that runs the talosctl apply under the hood or a command that generates the talosctl apply command so we can pipe it into bash.

Based on the discussions in issue #211 and in the k8s@home discord, we decided that if this is to be implemented, it will most likely be the 2nd option, allowing us to pipe said output.

Expected workflow:

With the following talconfig.yaml:

---
clusterName: home-cluster
talosVersion: v1.5.5
kubernetesVersion: v1.28.2
nodes:
  - hostname: cp-01.dev.k8s.mirceanton.com
    controlPlane: true
    ipAddress: 10.0.10

I should be able to do something along the lines of:

root@devbox:/workspace# talhelper gencommand --apply
talosctl apply-config --talosconfig ./clusterconfig/talosconfig --nodes 10.0.10.195 --file ./clusterconfig/home-cluster-cp-01.dev.k8s.mirceanton.com.yaml --insecure;

Thus allowing me to do something like this to bootstrap my cluster:

talhelper genconfig;
talhelper gencommand --apply | bash

For a single node this may seem trivial, but for clusters with multiple nodes, it easily becomes a quality of life improvement!