Add ESP-IDF 5 pulse_cnt driver support

[rvbc1]

Summary

This PR adds support for the new ESP-IDF 5 pulse counter driver API.

For ESP-IDF 5 and newer, ESP32Encoder now uses driver/pulse_cnt.h instead of the deprecated legacy driver/pcnt.h. The existing legacy implementation is kept for older ESP-IDF versions.

This addresses the deprecated PCNT driver warning reported in #117 without suppressing the warning.

Changes

• Add conditional PCNT driver selection based on ESP-IDF version.
• Use driver/pulse_cnt.h for ESP-IDF >= 5.
• Keep driver/pcnt.h for older ESP-IDF versions.
• Reimplement attach/detach/count/filter logic for the new PCNT API.
• Use PCNT watch points and accum_count for count accumulation.
• Preserve the existing public API.

Testing

• Compiled successfully with ESP-IDF 5.5 / Arduino ESP32 3.x based PlatformIO environment.
• Verified downstream firmware build using ESP32-S3.
• Tested encoder behavior locally on hardware.