fix(module:cascader): update position when click menu item

[yutao331763646]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[ ] No

Other information

[zorro-bot]

This preview will be available after the AzureCI is passed.

[yutao331763646]

与antd表现不一致

[codecov]

Codecov Report

Merging #7306 (edad65d) into master (2d77bc2) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #7306      +/-   ##
==========================================
+ Coverage   91.59%   91.60%   +0.01%     
==========================================
  Files         487      487              
  Lines       16006    16007       +1     
  Branches     2604     2604              
==========================================
+ Hits        14660    14663       +3     
+ Misses       1033     1032       -1     
+ Partials      313      312       -1     

Impacted Files	Coverage Δ
components/cascader/cascader.service.ts	99.51% <ø> (ø)
components/core/overlay/overlay-position.ts	90.90% <ø> (ø)
components/cascader/cascader.component.ts	97.98% <100.00%> (+<0.01%)	⬆️
components/tabs/tab-nav-bar.component.ts	87.94% <0.00%> (+0.70%)	⬆️

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[wzhudev]

LGTM. Thanks!

[yutao331763646]

目前的问题，如下图，当下拉选项超出屏幕时，会被遮挡

[yutao331763646]

修改之后：自动调整位置，使其剧中，和antd react体验保持一致，如下图

[simplejason]

LGTM