Adds a new command `talosctl gen secrets` to generate a `secrets.yaml` file with Talos and Kubenetes secrets. This file can later be used like `talosctl gen config ... --with-secrets secrets` to generate a config with these pre-generated secrets. Closessiderolabs/talos#5861.
Signed-off-by: Utku Ozdemir <utku.ozdemir@siderolabs.com>