Fix broken uart module

[aiotter]

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

uart module for ESP32 is broken. This PR fixes it.

• In the current code, uart:open/1,2 takes uart0, uart1 or uart2 as peripheral option. However, Nif takes either one of UART0, UART1 or UART2. This PR corrects the behaviour of uart:open to match that of Nif.
• The Nif of uart module does not send a reply parsable by port:call, which stops the process from executing further codes. This PR fixes that by using port_send_reply function.

[aiotter]

• The Nif of uart module does not send a reply parsable by port:call, which stops the process from executing further codes.

I noticed that there was another problem on my device which prevents me from processing UART. So this statement might be false. Actually I read the old code twice and cannot find problems. It seems I have to reword the commit comment and CHANGELOG.md to state that my commit is just a refactor.

[UncleGrumpy]

Thank you for this! We just discovered this bug and were discussing it in our Telegram chat, which I would encourage you to join:

https://t.me/atomvm

The core developers and many community members are frequently active there, and we would welcome having you join our conversations.

[aiotter]

Thank you for info about Telegram community. I already joined, but I seldom use Telegram, so I didn't noticed this PR is mentioned there.

If there is someone who wants to talk to me there, please don't hesitate to mention me. I'm there with the same username (@aiotter).

[bettio]

Just a couple of changes are still required. I think it can be good after that.
Let us know if the final PR works on real hardware as expected so we can merge it.
Thanks for all you did so far.

[aiotter]

Thank you for your review. The current code is already tested, in other words, the commits in the PR are cherry-picked from the branch I build AtomVM from and I'm using it in my daily development.

I'll check your review, correct the code ,reword the commit comment, test it on my device and let you know then.

[aiotter]

Tested and it worked. Now it's ready to be merged.