NzDrawerService创建的组件设置nzPlacement 为top时，超出的内容无法滚动

[zjxcv7]

What problem does this feature solve?

1、业务需要弹出一个全屏的面板时，面板中内容可能超出页面而导致显示不全

What does the proposed API look like?

内容超出可以滚动，或者设置组件的高度为100%时能够生效

[zorro-bot]

Translation of this issue:

When the component settings NzDrawerService created nzPlacement for the top, beyond the content can not scroll

What problem does this feature solve?

1, when business needs a full-screen pop-up panel, the panel may be beyond the contents of the page displays a result of incomplete

What does the proposed API look like?

To take effect when the content exceeds can scroll, or set the component height is 100%

[hsuanxyz]

@zjxcv7 当前版本 Drawer 样式的设计是有问题，ant-design 已经有很多 issues 了，很难做到在没有 break change 的情况下重构样式。

不过当前还是有解决办法的，先利用 nzWrapClassName 覆盖容器样式，再 nzBodyStyle 使其可滚动。

https://stackblitz.com/edit/angular-f4wene-pkswji?file=src/app/app.component.ts