Move to functional component 'Esercizio'

[grnsmn]

Goal is to move from class to functional component the 'Esercizio' component.
Is a good thingh use also a new name, maybe a good new name coulde be 'Breath' cause it is relative to breathing section.

Note: When convert make attention to the logic section needed for use audio click on timing, if found some good library to handle metronome is better