feat(module:input-number): add borderless support

[sebcam]

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

What is the current behavior?

Issue Number: #7389

What is the new behavior?

Input number can be displayed without border

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[codecov]

Codecov Report

Merging #7539 (e71ede5) into master (64b7389) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head e71ede5 differs from pull request most recent head c4825a6. Consider uploading reports for the commit c4825a6 to get more accurate results

@@            Coverage Diff             @@
##           master    #7539      +/-   ##
==========================================
- Coverage   91.75%   91.74%   -0.02%     
==========================================
  Files         502      502              
  Lines       16699    16700       +1     
  Branches     2604     2604              
==========================================
- Hits        15322    15321       -1     
- Misses       1047     1048       +1     
- Partials      330      331       +1     

Impacted Files	Coverage Δ
components/input-number/input-number.component.ts	99.60% <100.00%> (+<0.01%)	⬆️
components/tabs/tab-nav-bar.component.ts	87.23% <0.00%> (-0.71%)	⬇️

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