feat(module: select): support placement

[rorry121]

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
• [ ] 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?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[zorro-bot[bot]]

This preview will be available after the AzureCI is passed.

[codecov[bot]]

Codecov Report

Merging #7537 (e8b1f15) into master (aecb788) will decrease coverage by 0.04%. The diff coverage is 84.61%.

@@            Coverage Diff             @@
##           master    #7537      +/-   ##
==========================================
- Coverage   92.03%   91.99%   -0.05%     
==========================================
  Files         502      502              
  Lines       16736    16746      +10     
  Branches     2629     2631       +2     
==========================================
+ Hits        15403    15405       +2     
- Misses       1064     1072       +8     
  Partials      269      269              

Impacted Files	Coverage Δ
components/select/select.component.ts	91.29% <84.61%> (-0.33%)	:arrow_down:
components/table/src/table/tbody.component.ts	88.88% <0.00%> (-11.12%)	:arrow_down:
...ts/table/src/table/table-inner-scroll.component.ts	79.41% <0.00%> (-4.42%)	:arrow_down:
components/table/src/table/tr-measure.component.ts	86.95% <0.00%> (-4.35%)	:arrow_down:
components/tabs/tab-nav-bar.component.ts	87.23% <0.00%> (-0.71%)	:arrow_down:
components/core/util/text-measure.ts	92.98% <0.00%> (+0.87%)	:arrow_up:
components/table/src/table-style.service.ts	96.55% <0.00%> (+1.72%)	:arrow_up:

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