Refactor lmn_vpn role

- Separate `lmn_vpn` from `lmn_teacherlaptop`.
- Implement a check for the availability of the wireguard-server during the wg-config rollout.
- Enhance variable support with a standardized naming schema:
  - VPN selection via `vpn` variable (`none`, `wg`).
  - Wireguard configuration (endpoint, allowed IPs, ip_cdr, dns, searchpath).
- Run wg-config role in separate play with serial 1 to avoid conflicts, when the role attempts
  to determine the next free Wireguard IP on the server when role try to Add a check to verify if the radius certificate is revoked.
- Ensure required packages and services are only installed and configured if the `vpn` variable is set.
- Provide documentation for `lmn_vpn` module.

roles/lmn_vpn/defaults/main.yml

@@ -0,0 +1,9 @@
+---
+vpn: none
+ 
+# Wireguad config
+wg_endpoint: "203.0.113.1:51820"
+wg_allowed_ips: "10.0.0.0/16;"
+wg_ip_cdr: 24
+wg_dns: "9.9.9.9"
+wg_dns_search: "example.com"