support Modal.confirm({ icon: null }) to hide default Icon

[Adamwu1992]

First of all, thank you for your contribution! 😄

New feature please send pull request to feature branch, and rest to master branch.
Pull request will be merged after one of collaborators approve.
Please makes sure that these form are filled before submitting your pull request, thank you!

[中文版模板 / Chinese template]

🤔 This is a ...

• New feature
• Bug fix
• Site / document update
• Component style update
• TypeScript definition update
• Refactoring
• Code style optimization
• Branch merge
• Other (about what?)

👻 What's the background?

希望在调用Modal.confirm时可以省略图标

💡 Solution

Modal.confirm({
  icon: null,
  content: 'hello world'
})

📝 Changelog description

Describe changes from user side, and list all potential break changes or other risks.

No break changes.

☑️ Self Check before Merge

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• TypeScript definition is updated/provided or not needed
• Changelog is provided or not needed

[netlify]

Deploy preview for ant-design ready!

Built with commit 77c431b

https://deploy-preview-15319--ant-design.netlify.com

[afc163]

This pull request introduces 1 alert when merging dd44b0a6560f9bbe10953b63919be949bfc7d246 into b807859 - view on LGTM.com

new alerts:

• 1 for Unused variable, import, function or class

---

Comment posted by LGTM.com

[codecov]

Codecov Report

Merging #15319 into feature will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff            @@
##           feature   #15319   +/-   ##
========================================
  Coverage     94.1%    94.1%           
========================================
  Files          250      250           
  Lines         6635     6635           
  Branches      1938     1938           
========================================
  Hits          6244     6244           
  Misses         390      390           
  Partials         1        1

Impacted Files	Coverage Δ
components/modal/confirm.tsx	96.29% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[codecov]

Codecov Report

Merging #15319 into feature will increase coverage by 0.03%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##           feature   #15319      +/-   ##
===========================================
+ Coverage     94.1%   94.13%   +0.03%     
===========================================
  Files          250      250              
  Lines         6635     6635              
  Branches      1938     1906      -32     
===========================================
+ Hits          6244     6246       +2     
+ Misses         390      388       -2     
  Partials         1        1

Impacted Files	Coverage Δ
components/modal/confirm.tsx	96.29% <100%> (ø)	⬆️
components/upload/UploadList.tsx	96.33% <0%> (+1.83%)	⬆️

---

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 b807859...77c431b. Read the comment docs.

[afc163]

Mixed other commits, please clean up.