[feature request] PWM support

[Ayush1325]

I am working on some examples for PocketBeagle 2, and we have decided to use Rust for it.

I have a PWM example that currently uses a basic sysfs implementation. Since I am already using this crate for GPIOs, it would be nice to have PWM functionality here as well.

I can see that rust-sysfs-pwm exists, but seems to be unmaintained. So how would one go about adding PWM here. Should add the functionality here directly as a module, or would it be better to create PRs in rust-sysfs-pwm and build on top of it here.