[SearchBar] Support for trailing icon / avatar

Is your feature request related to a problem? Please describe.
Though it is mentioned in the anatomy of a SearchBar it seems not to be possible to add a trailing icon / avatar to it.

I tried to add a nested ImageView but it seems to be ignored. I also search for public methods, but not even in the class itself I was able to find any hint about avatar or trailing.

Describe the solution you'd like
Nesting an ImageView or a public setter.

Describe alternatives you've considered
Rebuilding the whole SearchBar from scratch custom

Additional context
It's about item 4:

We also happily accept pull requests.

Inizia dall’implementazione di SearchBar e dalla sezione anatomy collegata di Search.md, quindi esamina come vengono gestite le viste figlie e la personalizzazione pubblica. Determina se il risultato supportato debba essere un ImageView annidato, un setter pubblico o un’altra API, e considera come dovrebbero apparire l’icona finale o l’avatar nel componente.