Fix tree shift multiple

[labike]

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[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?

1. Describe the source of requirement.
   <a-directory-tree /> 无法使用shift多选

2. Resolve what problem.
   解决<a-directory-tree /> shift多选的问题

3. Related issue link.
   使用treeData属性的directory-tree无法正确使用shift全选 #1744

API Realization (Optional if not new feature)

1. Basic thought of solution and other optional proposal.
2. List final API realization and usage sample.
3. GIF or snapshot should be provided if includes UI/interactive modification.

What's the effect? (Optional if not new feature)

1. Does this PR affect user? Which part will be affected?
2. What will say in changelog?
3. Does this PR contains potential break change or other risk?

Changelog description (Optional if not new feature)

1. English description
   <a-directory-tree /> event shift can multiple

2. Chinese description (optional)
   <a-directory-tree>使用shift可以多选
   

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

Additional Plan? (Optional if not new feature)

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