Improve PCNT API (with HIL tests)

[Dominaezzz]

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Submission Checklist 📝

• I have updated existing examples or added new ones (if applicable).
• I have used cargo xtask fmt-packages command to ensure that all changed code is formatted correctly.
• My changes were added to the CHANGELOG.md in the proper section.
• My changes are in accordance to the esp-rs API guidelines

Extra:

• I have read the CONTRIBUTING.md guide and followed its instructions.

Pull Request Details 📖

Description

I've made a couple improvements to the API.

• Move pin inversion logic from config into the PcntSource struct.
• Lifetime of unit now restricted to the lifetime of the borrowed peripheral.
• Tie the configuration of limits/thresholds with the enabling of the event. The limits do nothing if the event is disabled.
• Provide separate unit objects so that Rust borrow checking can be taken advantage of.
• Split out upfront config object into multiple optional methods.
• Move counter to separate object which can be cloned. Eliminating the need for the critical section in the example.
• Fixed the use of write when disabling interrupts.
• Changed the interrupt check to look at INT_RAW instead of INT_ST.

Testing

I ran the HIL tests locally but CI should be good as well.
I'm unable to run the example.

[JurajSadel]

LGTM, thanks!

[bjoernQ]

LGTM - Thanks