network: Indicate the maximum password length accepted for wifi hotspots

The Wifi Hotspot setup dialog will error "Must have a minimum of 8 characters"
for all the situations in which nm_utils_wpa_psk_valid and nm_utils_wep_key_valid
report a given password to be invalid.

The case when this error is most obvious is when you enter a very lengthy password
and the dialog shows the very same error about the minimum password length.

These changes make the dialog account for the Maximum password length as well. It
assumes 16 characters for WEP and 63 characters for WPA/WPA2.
7 jobs for wifi-hotspot-psw-max-chars in 1 minute and 59 seconds (queued for 1 second)
Status Name Job ID Coverage
  Build
passed build #1288902

00:01:40

 
  Test
passed test #1288903

00:00:18

 
  Manual
manual asan #1288905
asan allowed to fail manual
manual flatpak #1288904
allowed to fail manual
manual msan #1288908
allowed to fail manual
manual tsan #1288906
allowed to fail manual
manual ubsan #1288907
allowed to fail manual