Add support for ESP32-C6

[xobs]

The ESP32-C6 is a brand-new part from Espressif. It should be similar to the ESP32-C3 in that it is also a RISC-V.

It would be nice to add support for this chip.

[alevy]

How similar is it to the ESP32-C3 in terms of peripherals? If it's similar the port should be pretty trivial.

You might notice, though, that support for the ESP32-C3 is.... minimal... In general, the things blocking supporting more chips/boards upstream are:

1. People interested in doing the port (if the port is easy, that's often easy to find)
2. Access to hardware to test for releases etc, or people able/willing to be on point to maintain and test

The ESPs are particularly tricky because the feature that most people seem to like the most (WiFi) isn't documented outside of a binary blob (as far as we know anyway).

[alistair23]

There is work to reverse engineer the WiFi blob: https://github.com/esp32-open-mac/esp32-open-mac