Fix WPS regression and cred conversion

[torkleyy]

Fixes #337
Also fixes the conversion of ssid/password in the config to no longer assume 0 termination - this lead to problems when routers send a 64 byte access token to us instead of a password

[ivmarkov]

Fixes #337 Also fixes the conversion of ssid/password in the config to no longer assume 0 termination - this lead to problems when routers send a 64 byte access token to us instead of a password

@torkleyy
For my understanding could you elaborate on the access token case you've mentioned?

[torkleyy]

I'm not quite sure how it works, but some routers will send 64-byte access tokens instead of the passphrase. Until now, the code assumed that ssid / password are always 0-terminated, but it's actually possible for them to use the maximum length of 32/64.

I had no success actually connecting to the Wifi using that token on the esp (it does work on other devices). I ended up setting CONFIG_ESP_WIFI_WPS_PASSPHRASE to receive the passphrase instead.

[ivmarkov]

I've delayed merging this for way too long, and now it has a conflict. :(
@torkleyy if you don't have time or will to resolve the conflicts in this PR, I'll understand and will do over the weekend.

(BTW: I've finally checked the (under-documented) ESP IDF Wifi API, and I confirm you are likely correct in the weird behavior w.r.t. SSID (and likely password) in that is is a null-terminated string except when it is full length).

[ivmarkov]

BTW, I'm worried that we might have other places to fix: specifically, the reverse conversion of native SSID into heapless::String SSID. But these we can of course fix later.

[torkleyy]

@ivmarkov rebased.

[ivmarkov]

Thank you!