esp32/network_ppp: Add authentication support to the PPP interface.
esp32/network_ppp: Add authentication support to the PPP interface.

This commit adds the connect() method to the PPP interface and requires
that connect() be called after active(1).  This is a breaking change for
the PPP API.

With the connect() method it's now possible to pass in authentication
information for PAP/CHAP, eg:

    ppp.active(1)
    ppp.connect(authmode=ppp.AUTH_PAP, username="user", "password="password")

If no authentication is needed simply call connect() without any
parameters.  This will get the original behaviour of calling active(1).

bvernoux/micropython,MrSurly/micropython,tobbad/micropython,pozetroninc/micropython,tobbad/micropython,henriknelson/micropython,trezor/micropython,pramasoul/micropython,pramasoul/micropython,selste/micropython,bvernoux/micropython,adafruit/circuitpython,kerneltask/micropython,pozetroninc/micropython,pramasoul/micropython,tobbad/micropython,bvernoux/micropython,adafruit/circuitpython,adafruit/circuitpython,selste/micropython,adafruit/circuitpython,selste/micropython,MrSurly/micropython,pramasoul/micropython,MrSurly/micropython,pramasoul/micropython,henriknelson/micropython,selste/micropython,bvernoux/micropython,adafruit/circuitpython,kerneltask/micropython,tobbad/micropython,pozetroninc/micropython,kerneltask/micropython,bvernoux/micropython,kerneltask/micropython,adafruit/circuitpython,henriknelson/micropython,henriknelson/micropython,MrSurly/micropython,selste/micropython,pozetroninc/micropython,kerneltask/micropython,trezor/micropython,trezor/micropython,tobbad/micropython,MrSurly/micropython,trezor/micropython,pozetroninc/micropython,trezor/micropython,henriknelson/micropython