fix(module:result): nz-result-icon in ng-content does not work

[Laffery]

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

[Laffery]

When nzIcon is undefined, the icon will be IconMap[this.nzStatus as NzResultIconType], which makes the icon always be truthy and the nz-result-icon is defined in the ng-content will not work forever

[codecov]

Codecov Report

❌ Patch coverage is 72.41379% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.06%. Comparing base (18b5f18) to head (904cdf6).
⚠️ Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
components/result/result.component.ts	72.41%	0 Missing and 8 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9511      +/-   ##
==========================================
- Coverage   90.11%   90.06%   -0.05%     
==========================================
  Files         570      570              
  Lines       23382    23379       -3     
  Branches     4644     4650       +6     
==========================================
- Hits        21070    21057      -13     
- Misses       1606     1614       +8     
- Partials      706      708       +2     

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[HyperLife1119]

LGTM