This commit consolidates a number of check_esp_err functions that check
whether an ESP-IDF return code is OK and raises an exception if not. The
exception raised is an OSError with the error code as the first argument
(negative if it's ESP-IDF specific) and the ESP-IDF error string as the
second argument.
This commit also fixes esp32.Partition.set_boot to use check_esp_err, and
uses that function for a unit test.
This commit adds an idf_heap_info(capabilities) method to the esp32 module
which returns info about the ESP-IDF heaps. It's useful to get a bit of a
picture of what's going on when code fails because ESP-IDF can't allocate
memory anymore. Includes documentation and a test.
