feat(binding): add support for binding whole request at once

[takanuva15]

With this PR, users can now call c.BindAll allow Gin to bind headers, request path params, query params, and body in a single call. This resolves a number of tickets regarding this functionality:

relates to #1824
relates to #2309
closes #2535
closes #2758
closes #2919
closes #4338
closes #3095
closes #4510

MVE:

package main

import (
  "net/http"

  "github.com/gin-gonic/gin"
)

type Person struct {
  Age       int       `header:"x-age" binding:"required"`
  ID        string    `uri:"id" binding:"required,uuid"`
  Name      string    `form:"name" binding:"required"`
  Addresses [2]string `json:"addresses" binding:"required"`
}

func main() {
  route := gin.Default()
  route.POST("/:id", func(c *gin.Context) {
    var person Person
    if err := c.ShouldBindAll(&person); err != nil {
      c.JSON(http.StatusBadRequest, gin.H{"msg": err.Error()})
      return
    }
    c.JSON(http.StatusOK, person)
  })
  route.Run(":8080")
}

Test it with:

curl -X POST -H "x-age:25" -H "Content-Type: application/json" -d '{"addresses":["foo","bar"]}' 'http://localhost:8080/987fbc97-4bed-5078-9f07-9141ba07c9f3?name=Bob'
# {"Age":25,"ID":"987fbc97-4bed-5078-9f07-9141ba07c9f3","Name":"Bob","addresses":["foo","bar"]}

Pull Request Checklist

Please ensure your pull request meets the following requirements:

• Open your pull request against the master branch.
• All tests pass in available continuous integration systems (e.g., GitHub Actions).
• Tests are added or modified as needed to cover code changes.
• If the pull request introduces a new feature, the feature is documented in the docs/doc.md.

Thank you for contributing!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.01%. Comparing base (3dc1cd6) to head (be6e758).
⚠️ Report is 249 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4543      +/-   ##
==========================================
- Coverage   99.21%   99.01%   -0.21%     
==========================================
  Files          42       46       +4     
  Lines        3182     3040     -142     
==========================================
- Hits         3157     3010     -147     
- Misses         17       21       +4     
- Partials        8        9       +1     

Flag	Coverage Δ
	?
--ldflags="-checklinkname=0" -tags sonic	99.01% <100.00%> (?)
go-1.18	?
go-1.19	?
go-1.20	?
go-1.21	?
go-1.25	99.01% <100.00%> (?)
macos-latest	99.01% <100.00%> (-0.21%)	⬇️
ubuntu-latest	?

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