first iteration of WiFiConnectionHandler with Dynamic SSID:PASS pair

[ubidefeo]

This PR adds a class which supports instantiation without SSID and PASS in order to dynamically set them at later time using setWiFiCredentials(String, String).
This allows a machine to get their WiFi credentials passed in at startup time via means of storage, effectively removing such credentials from the firmware.

[CLAassistant]

All committers have signed the CLA.

[ubidefeo]

@aentinger
I found out that I was behind on my local branch with some changes,
have now pulled the upstream, merged into my branch WiFiCredentials-dynamic and pushed again.
Strangely enough my version of Arduino_ConnectionHandler.h was missing the || defined(ARDUINO_NANO_RP2040_CONNECT) but it wasn't showing up in changed files.

It now appears to be aligned, please take a look and let me know if you want me to make changes

u.