esp32/network_lan: Add default arguments for network.LAN()

[sfe-SparkFro]

Description

Follow up from #19036 (comment)

Currently, network.LAN() requires the user to specify arguments for what pins to use, the PHY type, and the PHY address. This requires the user to dig through documentation, schematics, and possibly PHY datasheets to find these values. It would be much easier for these values to be defined in mpconfigboard.h so the user can simply call network.LAN() with no arguments to get the default LAN object for their board.

Code Size

This could be enabled per board, but I don't imagine it affecting code size significantly.

Implementation

I hope the MicroPython maintainers or community will implement this feature

Code of Conduct

Yes, I agree