socketpool/ssl: refactor to use micropython-style "stream protocol", enable MICROPY_PY_IO_IOBASE

[jepler]

After #7006 it would be possible to enable ssl without socketpool as a built-in module and instead use the "stream protocol" for ssl to perform operations like read/write/close on a socket.

If a different socket implementation such as https://github.com/adafruit/Adafruit_CircuitPython_Wiznet5k was changed to derive its sockets from io.IOBase, then its sockets could be successfully wrapped by an SSLContext.

[jepler]

Leaving this open as it's not resolved by #8954: Using read/write/ioctl "protocols" is a possible enhancement to the existing ability to use wiznet sockets. In particular, "ioctl" is needed to make select.poll (& therefore asyncio) work properlyl