esp32/modesp32: Add esp32.PCNT class.

Add a new `esp32.PCNT` class that provides complete, low-level support to
the ESP32 PCNT pulse counting hardware units.

This can be used as a building block to implement the higher-level
`machine.Counter` and `machine.Encoder` classes.

This is enabled by default on all OG, S2, S3, C6 boards, but not on C3 (as
the PCNT peripheral is not supported).

Original implementation by: Jonathan Hogg <me@jonathanhogg.com>

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
Signed-off-by: Angus Gratton <angus@redyak.com.au>

Author: jonathanhogg

ports/esp32/boards/sdkconfig.base

@@ -117,6 +117,7 @@ CONFIG_ADC_CAL_LUT_ENABLE=y
 CONFIG_UART_ISR_IN_IRAM=y
 
 # IDF 5 deprecated
+CONFIG_PCNT_SUPPRESS_DEPRECATE_WARN=y
 CONFIG_RMT_SUPPRESS_DEPRECATE_WARN=y
 
 CONFIG_ETH_USE_SPI_ETHERNET=y

ports/esp32/esp32_common.cmake

@@ -127,6 +127,7 @@ list(APPEND MICROPY_SOURCE_PORT
     modesp.c
     esp32_nvs.c
     esp32_partition.c
+    esp32_pcnt.c
     esp32_rmt.c
     esp32_ulp.c
     modesp32.c