esp32/machine_pwm: Improve PWM and make its API match other ports.

This reduce inconsistencies between esp32 PWM and other ports:
1. duty_u16() high value is 2**16-1 == 65535
2. Invert PWM wave with invert=1 parameter
3. Enable PWM in light sleep mode
4. Allow PWM output and read pulse input simultaneously on the same Pin()
5. Code refactoring

Co-Authored-By: Angus Gratton <[email protected]>
Co-Authored-By: robert-hh <[email protected]>
Co-Authored-By: Andrew Leech <[email protected]>
Co-Authored-By: Yoann Darche <[email protected]>

Signed-off-by: Ihor Nehrutsa <[email protected]>

Author: IhorNehrutsa