refactor(module: form): make validate mode default to Complex

[ElderJames]

🤔 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
• Other (about what?)

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💡 Background and solution

📝 Changelog

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🇨🇳 Chinese

☑️ Self Check before Merge

⚠️ Please check all items below before review. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
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[github-actions]

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 43.21%. Comparing base (3ad90ba) to head (2143f35).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
components/form/Form.razor	0.00%	1 Missing ⚠️
components/form/Form.razor.cs	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #4163       +/-   ##
===========================================
+ Coverage    1.40%   43.21%   +41.80%     
===========================================
  Files         585      586        +1     
  Lines       29730    29797       +67     
  Branches     5872     5897       +25     
===========================================
+ Hits          419    12877    +12458     
+ Misses      29271    15846    -13425     
- Partials       40     1074     +1034     

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