Allow manual entry of WiFi credentials from webserver (ESP32 configuration)

[heyitsyang]

Is your feature request related to a problem? Please describe.
Related to issue #141, but should done for hidden WiFi networks regardless

Describe the solution you'd like
Allow manual entry of WiFi credentials from webserver page (192.168.4.1)

Describe alternatives you've considered
Add option to add WiFi credentials manually independently of scanning for networks.

Additional context
Add any other context or screenshots about the feature request here.

[SisyphusMD]

Agreed, this would be helpful when connecting to networks with a hidden SSID.

[corgan2222]

Fixed in my fork
https://github.com/corgan2222/ESPresense

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.