feat: add json serialisation support for golang

[Souvikns]

Description

This PR is adding JSON serialization support by adding struct tags while generating go structs, by creating a new GO_PRESET.

package models

type AsyncApi_3Dot_0Dot_0SchemaDot struct {
  Asyncapi string `json:"asyncapi"`
  Id string `json:"id"`
  Info *Info `json:"info"`
  Servers map[string]interface{} `json:"servers"`
  DefaultContentType string `json:"defaultContentType"`
  Channels map[string]interface{} `json:"channels"`
  Operations map[string]interface{} `json:"operations"`
  Components *Components `json:"components"`
  AdditionalProperties map[string]interface{} `json:"-"`
}

Also adds custom marshaler functions for enums when generating struct-tags

func (op *ApiKeyIn) UnmarshalJSON(raw []byte) error {
	var v any
	if err := json.Unmarshal(raw, &v); err != nil {
		return err
	}
	*op = ValuesToApiKeyIn[v]
	return nil
}

func (op ApiKeyIn) MarshalJSON() ([]byte, error) {
	return json.Marshal(op.Value())
} 
          

Related Issue

Fixes #299

Checklist

• The code follows the project's coding standards and is properly linted (npm run lint).
• Tests have been added or updated to cover the changes.
• Documentation has been updated to reflect the changes.
• All tests pass successfully locally.(npm run test).

Additional Notes

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[jonaslagoni]

Only one comment for the implementation 👍 Looking good 💪

Remember to do parts 4 and 5 of https://github.com/asyncapi/modelina/blob/master/docs/contributing.md#adding-a-new-preset

[coveralls]

Pull Request Test Coverage Report for Build 8183449856

Details

• 17 of 18 (94.44%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.03%) to 92.27%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/generators/go/presets/CommonPreset.ts	14	15	93.33%

Totals
Change from base Build 8062206205:	-0.03%
Covered Lines:	6010
Relevant Lines:	6342

---

💛 - Coveralls

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[jonaslagoni]

LGTM 👍

[jonaslagoni]

/rtm

[jonaslagoni]

/rtm

[jonaslagoni]

@all-contributors please add @Souvikns for code, test, example, docs

[allcontributors]

@jonaslagoni

I've put up a pull request to add @Souvikns! 🎉

[asyncapi-bot]

🎉 This PR is included in version 4.0.0-next.12 🎉

The release is available on:

• npm package (@next dist-tag)
• GitHub release

Your semantic-release bot 📦🚀