feat(tabs): Enable rendering tabs list and tab content in independent locations

#### Feature Description

Currently, `MatTabGroup` renders the tab content immediately below the list of tab labels:
```
[ Tab 1 ] [ Tab 2 ] [ Tab 3 ]
-----------------------------
Tab content
```
This new feature will enable consumers to specify a separate location where the tab content should be rendered.

#### Use Case

The goal is to render content between the tab labels and tab content.

Example:
```
[ Tab 1 ] [ Tab 2 ] [ Tab 3 ] [ Button ]
---------------------------------------------------
Tab content
```

Usage example:
```

Content 1
Content 2
Content 3

Button

```

#### Contribution

I have an in progress PR that I will link to this issue.

从 issue 中描述的 MatTabGroup 行为开始，并查看提供的使用示例。完成的标准是 consumers 可以将标签页内容独立于标签页标签进行放置，并在指定的单独位置渲染内容。

由索引模型根据 Issue 内容生成。