Button controller

[rafacouto]

It's needed a button controller implementing this basic trait functions:

• is_pressed() -> bool
• changed() -> bool

The implementation should allow to specify if the button is hardware pulled down (gpio low/float) or up (gpio float/high) to manage with the right logic:

• new(pin: InputPin, pulled_up: bool) -> Self

[rafacouto]

The #31 code includes a simple implementation of ButtonController in Button struct as a simple button that includes a last_state field in order to know where the hardware gpio changes the state. A future complex implementation should manage the state changes via hardware interrupt.

An example for mithybuga board is included:

https://github.com/aindustriosa/RustyBugA/assets/969061/2bbd2082-b8e8-44d6-b7d3-f15f4a3d9292