feat(module: cascader): display indicator when options is null or empty

[noctis0430]

🤔 This is a ...

• New feature
• Bug fix
• Site / documentation update
• Demo update
• Component style update
• Bundle size optimization
• Performance optimization
• Refactoring
• Code style optimization
• Test Case
• Branch merge
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🔗 Related issue link

💡 Background and solution

📝 Changelog

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🇨🇳 Chinese

☑️ Self Check before Merge

⚠️ Please check all items below before review. ⚠️

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[github-actions]

[codecov]

Codecov Report

Merging #2108 (bb21336) into master (2cf5db5) will increase coverage by 1.94%.
The diff coverage is 62.50%.

@@            Coverage Diff             @@
##           master    #2108      +/-   ##
==========================================
+ Coverage   27.95%   29.89%   +1.94%     
==========================================
  Files         492      515      +23     
  Lines       32510    24762    -7748     
  Branches        0      240     +240     
==========================================
- Hits         9087     7403    -1684     
+ Misses      23423    17323    -6100     
- Partials        0       36      +36     

Impacted Files	Coverage Δ
components/cascader/Cascader.razor.cs	22.28% <0.00%> (+4.44%)	⬆️
components/cascader/Cascader.razor	83.22% <83.33%> (+9.31%)	⬆️
components/core/Helpers/MemberPath/PathNode.cs	46.15% <0.00%> (-8.85%)	⬇️
components/core/Reflection/TypeDefined.cs	77.77% <0.00%> (-7.94%)	⬇️
components/input/InputGroup.razor.cs	87.50% <0.00%> (-6.95%)	⬇️
...ponents/date-picker/types/DatePickerPlaceholder.cs	22.72% <0.00%> (-4.20%)	⬇️
...ponents/core/Component/Overlay/type/TriggerType.cs	81.25% <0.00%> (-2.97%)	⬇️
components/core/Component/Overlay/Overlay.razor.cs	65.89% <0.00%> (-2.86%)	⬇️
components/core/Helpers/DateHelper.cs	80.00% <0.00%> (-2.71%)	⬇️
...nts/core/Component/Overlay/OverlayTrigger.razor.cs	53.47% <0.00%> (-2.50%)	⬇️
... and 425 more

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[ElderJames]

I also found the clear button an issue. You can fix it in this PR, or you can open another one.

[noctis0430]

I also found the clear button an issue. You can fix it in this PR, or you can open another one.

Ok. Will try to fix it in this PR.

[noctis0430]

I also found the clear button an issue. You can fix it in this PR, or you can open another one.

Just found out the clear button issue is a separated issue. Maybe we should close this and open another one for it. @ElderJames what do you think?

[noctis0430]

I also just found out that there's an existing default image to indicate empty options.

Default image

Image in <Empty/> introduced in this PR

For the sake of consistency, we should pick and use only one. Which should we choose?

[ElderJames]

This one.