mat-icon: mat-icon doesn't fully support outlined, rounded, sharp and two tone

#### Feature Description

Current implementation of `mat-icon` is incomplete, we can only use icons of filled style. We need a way to easily use outlined, rounded, sharp and two tone variant of material icons, something looking like:
```html

```

#### Use Case

Currently, using outlined, rounded, sharp and two tone variant of material icons is really inconvenient. We need to use some workaround, like
```javascript
@import url("https://fonts.googleapis.com/icon?family=Material+Icons|Material+Icons+Outlined");
```
```html
home
```
which is discussed in https://github.com/angular/components/issues/11544, and this method does not make use of `mat-icon`, as it's a general web solution to use oulined icons.

Inizia esaminando l’implementazione attuale di mat-icon e la discussione correlata nell’issue 11544. Conferma come vengono selezionate attualmente le icone filled, quindi definisci come esporre tramite mat-icon le varianti outlined, rounded, sharp e two-tone; il lavoro sarà considerato completato quando ogni variante richiesta funzionerà senza il workaround CSS documentato.

Scritto dal modello di indicizzazione a partire dal testo della issue.