asyncio bugfixes, select bugfixes & selectable socket

[jepler]

1. The internal definition of ticks in moduasyncio was still wrong, in a way that deceptively seemed to work sometimes
2. select() was not interruptable with ctrl-c
3. socket objects are now selectable -- implementation tested on rp2040 only at this point -- needs further changes in asyncio module itself

Here's my test program, which connects to a netcat -l 5153 already running on my laptop bert. When I type something into netcat and hit enter, it's received and echoed back, with extra running commentary in the repl. also, the led toggles with each print.

@furbrain pinging in case you are interested in this

import os
import asyncio

import board
import digitalio
import socketpool
import wifi

if wifi.radio.ipv4_address is None:
    ssid = os.getenv('CIRCUITPY_WIFI_SSID')
    print("Connecting to", ssid)
    wifi.radio.connect(ssid, os.getenv('CIRCUITPY_WIFI_PASSWORD'))
    print("Connected to", ssid)
else:
    print("already connected")
print("Local address", wifi.radio.ipv4_address)

pool = socketpool.SocketPool(wifi.radio)


class Socket:
    def __init__(self, s):
        self.s = s
        s.setblocking(False)

    async def recv_into(self, buf):
        await asyncio.core._io_queue.queue_read(self.s)
        return self.s.recv_into(buf)

    async def send(self, buf):
        await asyncio.core._io_queue.queue_write(self.s)
        return self.s.send(buf)

async def sock_task(sock):
    print("in sock task")
    with digitalio.DigitalInOut(board.LED) as led:
        led.switch_to_output(False)
        s = Socket(sock)
        buf = bytearray(16)
        while True:
            led.value = not led.value
            print("going to await recv")
            sz = await s.recv_into(buf)
            print(sz, bytes(buf[:sz]))
            print("going to await send")
            sz = await(s.send(buf[:sz]))
            print("sent", sz)

with pool.socket(pool.AF_INET, pool.SOCK_STREAM) as sock:
    print("connecting")
    sock.connect(("bert.u", 5123))
    print("running task")
    asyncio.run(sock_task(sock))

[dhalbert]

Not tested. This looks good and I checked the ticks() stuff.