examples/VM: sless_job provisioning (packages, nginx, docker)

- Add sless.tf: three sless_job resources with depends_on chain
  - vm-install-packages: jq, python3-pip, htop, unzip
  - vm-install-nginx: nginx 1.18 (HTTP 200 verified)
  - vm-install-docker: Docker CE 29.3.1 + Compose v5.1.1
- Add functions/install-{packages,nginx,docker}/handler.py
  - _wait_apt_lock: cloud-init status --wait + systemctl mask
    fixes Ubuntu 22.04 first-boot apt lock (unattended-upgrades)
  - DPkg::Lock::Timeout=600 on all apt-get calls
- Add variables.tf (install_run_id, vm_public_key, vm_private_key)
- Add outputs.tf (install_*_result)
- Bump nubes provider 5.0.49 -> 5.0.51
- doc/progress.md: document step 6 with bug analysis

examples/VM/main.tf

@@ -5,7 +5,11 @@ terraform {
   required_providers {
     nubes = {
       source  = "terra.k8c.ru/nubes/nubes"
-      version = "5.0.49"
+      version = "5.0.51"
+    }
+    sless = {
+      source  = "terra.k8c.ru/naeel/sless"
+      version = "~> 0.1"
     }
   }
 }