Support for custom hostname in settings.toml

[jdimpson]

Would like a way to do the equivalent of setting wifi.radio.hostname="newhostname" prior to calling wifi.radio.connect(), but via settings.toml so that the CPy dhcp client requests "newhostname" along with requesting an IP address. This way it would take effect when using web workflow.

I tried assigning to CIRCUITPY_WEB_INSTANCE_NAME but that didn't seem to affect what hostname the dhcp client requests. Presumably something like CIRCUITPY_WIFI_HOSTNAME would be more appropriate.

[dhalbert]

Could you open this in https://github.com/adafruit/circuitpython instead? It's a core CircuitPython issue, not the web editor. Thanks.