fix(module:slider): fix range slider not working for arrow keys

[stygian-desolator]

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?

[x] 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

close #6586

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[zorro-bot]

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[codecov]

Codecov Report

Merging #6612 (7bda9f9) into master (48a9714) will decrease coverage by 0.02%.
The diff coverage is 85.71%.

❗ Current head 7bda9f9 differs from pull request most recent head 75c38f3. Consider uploading reports for the commit 75c38f3 to get more accurate results

@@            Coverage Diff             @@
##           master    #6612      +/-   ##
==========================================
- Coverage   89.90%   89.88%   -0.03%     
==========================================
  Files         481      481              
  Lines       15379    15388       +9     
  Branches     2344     2348       +4     
==========================================
+ Hits        13827    13831       +4     
- Misses        935      938       +3     
- Partials      617      619       +2     

Impacted Files	Coverage Δ
components/image/image-config.ts	100.00% <ø> (ø)
components/modal/modal-config.ts	100.00% <ø> (ø)
components/slider/slider.component.ts	90.40% <60.00%> (-0.54%)	⬇️
components/core/time/candy-date.ts	86.75% <100.00%> (+0.17%)	⬆️
components/date-picker/date-picker.component.ts	93.37% <100.00%> (ø)
components/date-picker/date-picker.service.ts	100.00% <100.00%> (ø)
...mponents/date-picker/date-range-popup.component.ts	90.42% <100.00%> (+0.64%)	⬆️
components/date-picker/picker.component.ts	91.76% <100.00%> (ø)
components/table/src/table/tr-measure.component.ts	86.95% <0.00%> (-13.05%)	⬇️
components/table/src/table/tbody.component.ts	88.88% <0.00%> (-11.12%)	⬇️
... and 5 more

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[wenqi73]

@wendellhu95 Please review this.

[hsuanxyz]

Suggested change

	(keydown)="onHandleKeyDown(handleIndex)"
	(focusin)="onHandleKeyDown(handleIndex)"

Is it possible to use focusin here?

[stygian-desolator]

updated, pls review it again~

[wzhudev]

LGTM. Thanks!