feat(module:button): support link type

[hsuanxyz]

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
[ ] 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
[x] No

Other information

[netlify]

Deploy preview for ng-zorro-master ready!

Built with commit 68f7bad

https://deploy-preview-3503--ng-zorro-master.netlify.com

[netlify]

Deploy preview for ng-zorro-master ready!

Built with commit 58587d9

https://deploy-preview-3503--ng-zorro-master.netlify.com

[codecov]

Codecov Report

Merging #3503 into master will decrease coverage by 0.04%.
The diff coverage is 65%.

@@            Coverage Diff             @@
##           master    #3503      +/-   ##
==========================================
- Coverage    95.6%   95.56%   -0.05%     
==========================================
  Files         609      609              
  Lines       13250    13264      +14     
  Branches     1810     1812       +2     
==========================================
+ Hits        12668    12676       +8     
- Misses        197      200       +3     
- Partials      385      388       +3

Impacted Files	Coverage Δ
components/button/demo/basic.ts	100% <ø> (ø)	⬆️
components/button/demo/disabled.ts	100% <ø> (ø)	⬆️
components/button/demo/size.ts	100% <ø> (ø)	⬆️
components/button/nz-button.component.ts	94.11% <ø> (ø)	⬆️
components/button/demo/ghost.ts	100% <ø> (ø)	⬆️
components/button/demo/block.ts	100% <ø> (ø)	⬆️
components/core/wave/nz-wave.directive.ts	85% <64.28%> (-11.16%)	⬇️
components/core/wave/nz-wave-renderer.ts	87.87% <66.66%> (ø)	⬆️
components/select/nz-option-container.component.ts	95.34% <0%> (-2.33%)	⬇️

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[wzhudev]

LGTM