Feature: Add hardware PWM support

[cvpines]

Adds hardware PWM support to libDaisy.

Introduces the PWMHandle class that provides up to 4 channels of PWM output per timer peripheral.
Also includes a small demo project showing how to use the class.

This API has been extensively tested on the Daisy Seed and shown to work for every supported timer and channel.

Minimal example:

PWMHandle pwm_tim3;
pwm_tim3.Init({PWMHandle::Config::Peripheral::TIM_3});
pwm_tim3.Channel1().Init({seed::D19});
pwm_tim3.Channel1().Set(0.75f);

[cvpines]

Review very much welcomed! 🙂

[stephenhensley]

Thank you for the contribution! This has been a much needed feature since libDaisy came into being.

I'll carve out some time to do a full review next week, but at a glance it looks great! Conforms to typical libDaisy conventions, and has a straightforward API for usage.

[github-actions]

Test Results

150 tests  ±0   150 ✅ ±0   0s ⏱️ ±0s
  1 suites ±0     0 💤 ±0 
  1 files   ±0     0 ❌ ±0 

Results for commit cde6250. ± Comparison against base commit f7c63ae.

♻️ This comment has been updated with latest results.

[stephenhensley]

This looks great, and works great!
Did a little bit of testing, and looks good to me!

I saw a few more changes come in last night, @cvpines anything else you want to do before we merge this in?

[cvpines]

Good on my end!

[stephenhensley]

Awesome, thanks again for the awesome PR!