Fixes and small refactor of wpa_supplicant config generation
This MR is a follow-up of !826 (merged).
The biggest changes are:
- refactors the way
key_mgmt
of the wpa_supplicant config gets generated (this is kind of optional, but I think it's way cleaner) - makes PMF necessary for all WPA3 AKM suites
- Use wpa-psk as key-mgmt instead of sae when AP support both WPA2 and WPA3