Re-implement WPA-EAP connection builder following NetworkManager D-Bus schema

[cachebag]

Overview:
After reverting wifi_builders.rs, WPA-EAP (think eduroam-style or company networks) connections are no longer supported.
The previous implementation failed because it set incomplete D-Bus properties for 802-11-wireless-security and 802-1x.
We need a clean re-implementation that builds EAP connections according to NetworkManager’s documented schema.

References:

• NetworkManager D-Bus API Reference
• NetworkManager Spec: Settings and 802.1x
• Example: add-wifi-eap-connection.py

Tasks:

• Review correct D-Bus keys for wpa-eap and 802-1x sections
• Implement a validated builder in wifi_builders.rs
• Add tests for PEAP and TTLS variants
• Confirm PSK and open connections remain unaffected

[cachebag]

Moving to #56 since this is mostly covered now