feat(module:input): textarea supports character count

[yangjunhan]

close #5907

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: #5907

What is the new behavior?

It now supports displaying character count at the bottom-right corner below the textarea. User can customize max length and character count computation function.

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 #6104 (8ab5043) into master (7ef2ed0) will decrease coverage by 0.03%.
The diff coverage is 84.00%.

@@            Coverage Diff             @@
##           master    #6104      +/-   ##
==========================================
- Coverage   89.86%   89.82%   -0.04%     
==========================================
  Files         467      468       +1     
  Lines       14214    14238      +24     
  Branches     2238     2238              
==========================================
+ Hits        12773    12789      +16     
- Misses        890      893       +3     
- Partials      551      556       +5     

Impacted Files	Coverage Δ
components/input/input.module.ts	100.00% <ø> (ø)
components/input/textarea-count.component.ts	84.00% <84.00%> (ø)
components/core/util/text-measure.ts	89.56% <0.00%> (-1.74%)	⬇️
components/tabs/tab-nav-bar.component.ts	81.62% <0.00%> (-0.71%)	⬇️
components/tree/tree-indent.component.ts	100.00% <0.00%> (ø)
components/tree/tree-node.component.ts	91.07% <0.00%> (+0.10%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 7ef2ed0...8ab5043. Read the comment docs.

[Airblader]

This doesn't need to be static: true, does it?

[hsuanxyz]

thx review, dynamic content will make matching targets more complex, in which case I think it's enough for developers.

[Airblader]

The static flag isn't about dynamic content, it's about lifecycle, and static true is deprecated so it has to be removed anyway. In here it can be removed without any additional effort.