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.

首先查看当前的 mat-icon 实现以及 issue 11544 中的相关讨论。确认当前如何选择 filled 图标，然后确定应如何通过 mat-icon 暴露 outlined、rounded、sharp 和 two-tone 变体；完成的标准是每个请求的变体都能在不使用文档中所述 CSS 变通方案的情况下正常工作。

由索引模型根据 Issue 内容生成。