feat: generate formData params via go struct

[BLumia]

Describe the PR
Allow generate params for formData by using go struct.

Relation issue
Intended to resolve #300

Additional context
go test passed even if I didn't change anything related to the unit test, it seems the old test doesn't cover this case. I didn't add any extra test cases for this PR since I'm not sure about how to write unit test for this case. Hope that's okay.

btw if this PR can get merged, the documentation may also need to update.

[codecov]

Codecov Report

Merging #770 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #770   +/-   ##
=======================================
  Coverage   82.16%   82.16%           
=======================================
  Files           8        8           
  Lines        1744     1744           
=======================================
  Hits         1433     1433           
  Misses        193      193           
  Partials      118      118           

Impacted Files	Coverage Δ
operation.go	88.46% <100.00%> (ø)

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[birdycn]

How to use

[BLumia]

How to use

The same as when using with query

[birdycn]

How to use

The same as when using with query

type Params struct{
  File *multipart.FileHeader `form:"file"
}

How to write tag

[BLumia]

Please consider Read The Fantastic Manual.

(ps. use the form: prefix instead of json:)

btw, if you still got issues, I suggest you open a new issue thread instead of reply in the merged PR.