This commit implements basic NVS support for the esp32. It follows the
pattern of the esp32.Partition class and exposes an NVS object per NVS
namespace. The initial support provided is only for signed 32-bit integers
and binary blobs. It's easy (albeit a bit tedious) to add support for
more types.
See discussions in: #4436, #4707, #6780
This commit adds support for building the esp32 port with cmake, and in
particular it builds MicroPython as a component within the ESP-IDF. Using
cmake and the ESP-IDF build infrastructure makes it much easier to maintain
the port, especially with the various new ESP32 MCUs and their required
toolchains.
Signed-off-by: Damien George <damien@micropython.org>
