feat(module:icon): support nz-icon tag selector

[HyperLife1119]

PR Checklist

Please check if your PR fulfills the following requirements:

• [x] The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd/blob/master/CONTRIBUTING.md#commit
• [x] Tests for the changes have been added (for bug fixes / features)
• [x] 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?

新版本更推荐使用 <nz-icon> 而非 <span nz-icon>，前者更简短清晰，且支持自闭合。

+ <nz-icon nzType="smile" />
- <span nz-icon nzType="smile"></span>

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Other information