WIFI Hostname should be device specific, not "toit"

[xal88]

Is your feature request related to a problem? Please describe.
Every ESP with the TOIT Firmware connects to Wifi and announces the same hostname : "toit"
If you have many toit devices its difficult to see which is which on the routers gui., and needs manual renaming.

Describe the solution you'd like
The device hostname should contain the devicename, like "toit-myiot1".

Filter to ASCII(7) letters from a to z, the digits from 0 to 9, and the hyphen (-). with max length of 63 char.

Describe alternatives you've considered
use the last digits of the deviceID as identifier.