fix(module:button): fix add class ant-btn-icon-only(#7631)

[withOutUndo]

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: 7631

What is the new behavior?

add class ant-btn-icon-only to button

Does this PR introduce a breaking change?

[ ] Yes
[x] No

[codecov]

Codecov Report

Merging #7678 (b62a22c) into master (538ef21) will increase coverage by 0.00%.
The diff coverage is 83.33%.

❗ Current head b62a22c differs from pull request most recent head bf01358. Consider uploading reports for the commit bf01358 to get more accurate results

@@           Coverage Diff           @@
##           master    #7678   +/-   ##
=======================================
  Coverage   91.78%   91.78%           
=======================================
  Files         509      509           
  Lines       17444    17434   -10     
  Branches     2772     2681   -91     
=======================================
- Hits        16011    16002    -9     
  Misses       1134     1134           
+ Partials      299      298    -1     

Impacted Files	Coverage Δ
components/button/button.component.ts	98.52% <83.33%> (+1.09%)	⬆️

... and 1 file with indirect coverage changes

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[sebcam]

any plan to merge this ?

[wzhudev]

The code looks good to be. But a unit test would be good. :) @withOutUndo could you please add one?

[withOutUndo]

The code looks good to be. But a unit test would be good. :) @withOutUndo could you please add one?

add some tests for this

[wzhudev]

LGTM. Thanks.

[Zaleck-a]

when would this be merged?

[wzhudev]

@simplejason This could be merged in the next patch version.

[igorbremec]

Dear developers, please merge this already 🙏

Apps that dynamically load nz icons have been broken for a long while because of this. I've been waiting months for a fix so I can upgrade to the new version.