feat(module:form): support form label align

[TheBeard30]

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

[zorro-bot]

This preview will be available after the AzureCI is passed.

[codecov]

Codecov Report

Merging #7870 (ecd5996) into master (ea9969d) will decrease coverage by 0.01%.
The diff coverage is 11.11%.

❗ Current head ecd5996 differs from pull request most recent head 672fa9c. Consider uploading reports for the commit 672fa9c to get more accurate results

@@            Coverage Diff             @@
##           master    #7870      +/-   ##
==========================================
- Coverage   20.24%   20.24%   -0.01%     
==========================================
  Files         506      506              
  Lines       17304    17313       +9     
  Branches     2748     2749       +1     
==========================================
+ Hits         3504     3505       +1     
- Misses      13775    13783       +8     
  Partials       25       25              

Impacted Files	Coverage Δ
components/form/form.directive.ts	9.67% <0.00%> (-0.33%)	⬇️
components/form/form-label.component.ts	15.38% <12.50%> (-0.75%)	⬇️

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[simplejason]

LGTM