fix(Breadcrumb): items dropdownProps loss

[linxianxi]

[中文版模板 / Chinese template]

🤔 This is a ...

• New feature
• Bug fix
• Site / documentation update
• Demo update
• Component style update
• TypeScript definition update
• Bundle size optimization
• Performance optimization
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🔗 Related issue link

fix #43146

💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English	Fixed invalid dropdownProps for items
🇨🇳 Chinese	修复 items dropdownProps 无效的问题

☑️ Self-Check before Merge

⚠️ Please check all items below before requesting a reviewing. ⚠️

• 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

---

🚀 Summary

🤖 Generated by Copilot at 3a8ec93

Added a new prop dropdownProps to Breadcrumb component to allow customizing the Dropdown menu. Updated the overlay demo to show an example of using the new prop.

🔍 Walkthrough

🤖 Generated by Copilot at 3a8ec93

• Add dropdownProps property to BreadcrumbItemType interface and pass it to Dropdown component in Breadcrumb component (link, link, link, link)
• Remove redundant assignment of itemClassName to itemProps.className in Breadcrumb component (link)
• Change import order and add dropdownProps to last breadcrumb item in overlay.tsx demo (link, link)

[github-actions]

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (6b4afc9) 100.00% compared to head (8cc1bc5) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##            master    #43151   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          648       648           
  Lines        10960     10961    +1     
  Branches      2975      2975           
=========================================
+ Hits         10960     10961    +1     

Impacted Files	Coverage Δ
components/breadcrumb/Breadcrumb.tsx	100.00% <ø> (ø)

... and 1 file with indirect coverage changes

☔ View full report in Codecov by Sentry.
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[afc163]

加个用例？

[linxianxi]

加个用例？

done