ESP32: Support for RMT RX

[atanisoft]

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Is your feature request related to a problem? Please describe. I'm currently using the RMT to generate outbound (TX) data streams which appears to work in Wokwi, but I also have a use case for inbound (RX). I've currently implemented UART communication over RMT to support modes which the hardware UART is not able to support fully, as an example 9-bit "bytes" (9th bit is used by RS-485 main node to "ping" child nodes). Technically this can be implemented using the hardware UART but it requires a custom ISR handler to catch "parity mismatch" which can have other side effects that are undesirable.

Describe the solution you'd like It would be great to support RMT RX, it would need to capture the transition from high to low (or reverse) with accurate timing similar to what is used for TX.