菜单收缩时，放上鼠标弹出框没做窗口边界检测

[runFP]

Reproduction link

https://stackblitz.com/edit/ng-zorro-antd-start-aawfnx?file=src/app/app.component.html

Steps to reproduce

1.调整窗口大小尽量让菜单最下面的选项和窗口平行
2.移上鼠标
3.弹出框部分内容被遮蔽，遵循的位置策略为POSITION_MAP.topLeft, POSITION_MAP.topRight

What is expected?

能否暴露NzSubMenuComponent组件传给cdkConnectedOverlay的cdkConnectedOverlayPositions参数，
或者哪个服务可以在弹出框弹出时修改初始参数

What is actually happening?

弹出框，没做下边界检测，部分内容被遮蔽

Environment	Info
ng-zorro-antd	8.2.1
Browser	google chrome

[zorro-bot]

Translation of this issue:

When the menu is shrinking, do not put the mouse pop-up window boundary detection

Reproduction link

[Https://stackblitz.com/edit/ng-zorro-antd-start-aawfnx?file=src/app/app.component.html](https://stackblitz.com/edit/ng-zorro-antd- start-aawfnx? file = src / app / app.component.html)

Steps to reproduce

1. Try to resize the window so that the bottom of the menu options and windows parallel
2. Move the mouse
3. A pop-up box part is shielded position to follow the strategy of POSITION_MAP.topLeft, POSITION_MAP.topRight

What is expected?

NzSubMenuComponent assembly can pass cdkConnectedOverlay exposure of cdkConnectedOverlayPositions parameters,
Or services which may modify the initial parameters in the pop-up box pops up

What is actually happening?

Pop-up box, do not lower boundary detection, part obscured

Environment	Info
Ng-zorro-antd	8.2.1
Browser	google chrome