Implement async wifi connection on picow

[bill88t]

Fixes #7066.
Works*.

*Though for some reason cyw43_wifi_link_status, instead of returning CYW43_LINK_UP, returns CYW43_LINK_JOIN, even though we have ip and internet.
And while connecting, CYW43_LINK_JOIN is returned too..
So I have to wait for the timeout.

[bill88t]

Ah I should've been using cyw43_tcpip_link_status, fixed.

[jepler]

@BiffoBear can you test with the artifacts from this PR? they should be ready in an hour or so. If you're not familiar with how to get artifacts from a PR build let me know and I'll add more verbose instructions.

[bill88t]

Just so it's clear, I did test it. Usb appears just fine and serial is connectable.
I added a print("ok") after the connection, and I get to see it.

[BiffoBear]

@BiffoBear can you test with the artifacts from this PR? they should be ready in an hour or so. If you're not familiar with how to get artifacts from a PR build let me know and I'll add more verbose instructions.

I'm happy to test for you, but I've never got artifacts from a PR build before. So I will appreciate your instructions.

Also note that I won't be able to perform the tests for about 12 hours from the time of this post.

[dhalbert]

I'm happy to test for you, but I've never got artifacts from a PR build before. So I will appreciate your instructions.

Click on the "Details" link on a board build below.

Then click on the Summary link:

Then scroll on the Summary page to see the "Artifacts section:

Then you download the artifact .zip for the board, and extract the build you want from it.

[jepler]

I tested this and it still connects. I never had the problem of losing the USB connection, but it stands to reason that this change will address that. Even if it doesn't, this is a step in the right direction. Thank you!

[BiffoBear]

I'm happy to test for you, but I've never got artifacts from a PR build before. So I will appreciate your instructions.

Click on the "Details" link on a board build below. ![image](https://user-...

Hi Dan,

Thanks for taking the time to post these instructions. I didn't get to use them this time, but I've stored them for future reference and I'll play with them a bit, so I can learn a new skill.