fix: collect tree key should support nest children

[zombieJ]

🤔 This is a ...

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

🔗 Related issue link

fix #19644

💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English	Fix DirectoryTree defaultExpandedAll not work with treeData.
🇨🇳 Chinese	修复 DirectoryTree defaultExpandedAll 在使用 treeData 时不正确的问题。

☑️ 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

[tests-checker]

Could you please add tests to make sure this change works as expected?

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[codecov]

Codecov Report

Merging #19646 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #19646   +/-   ##
=======================================
  Coverage    97.8%    97.8%           
=======================================
  Files         284      284           
  Lines        7704     7704           
  Branches     2122     2170   +48     
=======================================
  Hits         7535     7535           
  Misses        169      169

Impacted Files	Coverage Δ
components/tree/util.ts	96.15% <100%> (ø)	⬆️

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