Implement embedded_hal 1 pwm traits for ledc channel

[Remmirad]

Implements embedded_hal_1::pwm::SetDutyCycle for ledc::channel::Channel.

Tries to handle max duty cycle resolution differences between embedded_hal and esp32 (16, 20).

Must

• The code compiles without errors or warnings.
• All examples work.
• cargo fmt was run.
• Your changes were added to the CHANGELOG.md in the proper section.
• You updated existing examples or added examples (if applicable). (Would only be a rough copy of the ledc example?)
• Added examples are checked in CI

Nice to have

• You add a description of your work to this PR.
• You added proper docs for your newly added features and code. (embedded_hal provides it)

[bjoernQ]

Looks good to me but probably you need to double check CHANGELOG.md since there was a release in the meantime and the entry would probably not go into the unreleased section

[Remmirad]

Thanks for the remark. I rebased and put the change in the new unreleased section.

[bjoernQ]

LGTM - Thanks!

[jessebraham]

LGTM, thanks!