refactor: add types definition for input

[hsuanxyz]

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)
[x] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[x] 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 TravisCI is passed.

[codecov]

Codecov Report

Merging #4575 into master will decrease coverage by 0.09%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master    #4575     +/-   ##
=========================================
- Coverage   93.33%   93.23%   -0.1%     
=========================================
  Files         504      519     +15     
  Lines       12772    12822     +50     
  Branches     2020     2013      -7     
=========================================
+ Hits        11921    11955     +34     
- Misses        437      452     +15     
- Partials      414      415      +1

Impacted Files	Coverage Δ
components/button/nz-button.component.ts	95.12% <ø> (ø)
components/tooltip/nz-tooltip-base.component.ts	92.64% <100%> (ø)	⬆️
components/card/nz-card.component.ts	100% <100%> (ø)	⬆️
components/modal/nz-modal.component.ts	96.19% <100%> (ø)	⬆️
components/popover/nz-popover.directive.ts	100% <100%> (ø)	⬆️
components/tooltip/nz-tooltip-base.directive.ts	95.52% <100%> (ø)	⬆️
components/popconfirm/nz-popconfirm.directive.ts	100% <100%> (ø)	⬆️
components/tooltip/nz-tooltip.directive.ts	100% <100%> (ø)	⬆️
components/empty/nz-empty.service.ts	95.65% <0%> (-4.35%)	⬇️
...otification/nz-notification-container.component.ts	96.87% <0%> (-3.13%)	⬇️
... and 98 more

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[wzhudev]

LGTM

[wzhudev]

@hsuanxyz Azure says "build not found". Perheps you could rebase to the lastest master?