Correctly handle 64 hex digit passkey

[billz]

A network defined in wpa_supplicant.conf may contain a passphrase, passkey or both. In cases where a known network exists with a valid 64-character passkey, but no passphrase, RaspAP will incorrectly throw a 'WPA passphrase must be between 8 and 63 characters' error.

Resolves #1397

# psk: WPA preshared key; 256-bit pre-shared key
# The key used in WPA-PSK mode can be entered either as 64 hex-digits, i.e.,
# 32 bytes or as an ASCII passphrase (in which case, the real PSK will be
# generated using the passphrase and SSID). ASCII passphrase must be between
# 8 and 63 characters (inclusive). ext:<name of external PSK field> format can
# be used to indicate that the PSK/passphrase is stored in external storage.

https://w1.fi/cgit/hostap/plain/wpa_supplicant/wpa_supplicant.conf