[FEATURE] Fix security fault: plain text WiFi SSID/PASSWORD stored at /data/wapi.conf

### Is your feature request related to a problem? Please describe.

Currently the wapi command uses plain text config to save WiFi password:

nsh> cat /data/wapi.conf
{"wlan0":{"mode":2,"auth":4,"cmode":8,"alg":3,"ssid":"Nuttx-IOT","bssid":"e0:1c:fc:00:??:??","psk":"espmint123"}}nsh>

### Describe the solution you'd like

We need to find some alternative to save it in a save way to avoid someone with access to the "nsh>" to find this password.

### Describe alternatives you've considered

_No response_

### Verification

- [x] I have verified before submitting the report.