Migrate remaining examples to riot4

[hudelgado]

Hi, if you need i can migrate the examples that aren't updated to riot4.

[GianlucaGuarini]

@hudelgado that would be great wherever it's possible. I think the router examples need to be on hold because the new Riot Router was not released yet. For all the others your help would be really appreciated. Thank you

[raxell]

Does make sense to migrate the mixin example? It seems equivalent to the plugin example in the doc.

[GianlucaGuarini]

naa we can delete it