Fixes#4138
When KubeSpan is enabled, Talos automatically generates or loads
KubeSpan identity which consists of Wireguard key pair. ULA address is
calculated based on ClusterID and first NIC MAC address.
Some code was borrowed from #3577.
Example:
```
$ talosctl -n 172.20.0.2 get ksi
NODE NAMESPACE TYPE ID VERSION ADDRESS PUBLICKEY
172.20.0.2 kubespan KubeSpanIdentity local 1 fd71:6e1d:86be:6302:e871:1bff:feb2:ccee/128 Oak2fBEWngBhwslBxDVgnRNHXs88OAp4kjroSX0uqUE=
```
Additional changes:
* `--with-kubespan` flag for `talosctl cluster create` for quick testing
* validate that cluster discovery (and KubeSpan) requires ClusterID and
ClusterSecret.
Signed-off-by: Andrey Smirnov <andrey.smirnov@talos-systems.com>
Signed-off-by: Seán C McCord <ulexus@gmail.com>
Co-authored-by: Seán C McCord <ulexus@gmail.com>
Fixes#4137
Node identity is established when `STATE` partition is mounted, and
cached there. Node identity will be used for the cluster discovery
process to identify each node of the cluster.
Random 32 bytes encoded via base62 are used as node identity.
`base62` uses only URL-safe characters which might save us some trouble
later.
Signed-off-by: Andrey Smirnov <andrey.smirnov@talos-systems.com>
