chore: Add legacy test [part 1]

[zombieJ]

Part 1

Please help to check related document update about this: https://github.com/react-component/field-form/blob/f4c9c586d5a8ea4ed31f7934528b9800cbf0b8bf/README.md#different-with-rc-form

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[codecov]

Codecov Report

Merging #8 into master will increase coverage by 6.17%.
The diff coverage is 97.22%.

@@            Coverage Diff             @@
##           master       #8      +/-   ##
==========================================
+ Coverage   76.75%   82.93%   +6.17%     
==========================================
  Files          13       13              
  Lines         641      662      +21     
  Branches      120      121       +1     
==========================================
+ Hits          492      549      +57     
+ Misses        149      113      -36

Impacted Files	Coverage Δ
src/FieldContext.ts	75% <ø> (ø)	⬆️
src/utils/asyncUtil.ts	95% <100%> (+0.55%)	⬆️
src/Field.tsx	91.94% <100%> (+3.59%)	⬆️
src/useForm.ts	84.23% <100%> (+10.07%)	⬆️
src/utils/validateUtil.ts	96.38% <85.71%> (-1.12%)	⬇️
src/Form.tsx	70.27% <0%> (+2.7%)	⬆️
src/utils/valueUtil.ts	91.22% <0%> (+21.05%)	⬆️

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