Light-/deep-sleep support for ESP32-C6

[jessebraham]

This will serve as a tracking issue for light-/deep-sleep support for the ESP32-C6.

Work in this area is already underway:

• C6 PMU startup configuration #974
• C6 deep sleep driver MVP #918
• Wakeup sources other than EXT1
• Various system state save/restore for light sleep

Please feel free to use this issue for any related discussion. I will add relevant pull requests above as they are opened.

[jessebraham]

#918 has been merged. I know this isn't feature-complete yet, @bugadani are you able to summarize what's left to do? Or should we just close this issue now?

[bugadani]

There are two main areas that I ignored so far:

• wakeup sources other than EXT1
• various system state save/restore for light sleep

[bjoernQ]

We now have working basic light-sleep and a few more wakeup-sources. I think for remaining features we should have separate issues as needed instead of keeping this issue open forever