[REQ] [GO] Added enumClassPrefix option to go-gin-server. Used same appro…

[pmcgleenon]

#8680 (go-server)

Added enumClassPrefix option for go-gin-server target. This option already exists in go-server.
Fixed a bug in the model.mustache where name is used in the type declaration and classname is used in the definition

generated code before:

`type ComparisonOperator_anyOf string

// List of ComparisonOperator_anyOf
const (
        EQ ComparisonOperatorAnyOf = "EQ"
        NEQ ComparisonOperatorAnyOf = "NEQ"
        GT ComparisonOperatorAnyOf = "GT"
        GTE ComparisonOperatorAnyOf = "GTE"
        LT ComparisonOperatorAnyOf = "LT"
        LTE ComparisonOperatorAnyOf = "LTE"
)`

generated code after:

`type ComparisonOperatorAnyOf string

// List of ComparisonOperatorAnyOf
const (
        COMPARISONOPERATORANYOF_EQ ComparisonOperatorAnyOf = "EQ"
        COMPARISONOPERATORANYOF_NEQ ComparisonOperatorAnyOf = "NEQ"
        COMPARISONOPERATORANYOF_GT ComparisonOperatorAnyOf = "GT"
        COMPARISONOPERATORANYOF_GTE ComparisonOperatorAnyOf = "GTE"
        COMPARISONOPERATORANYOF_LT ComparisonOperatorAnyOf = "LT"
        COMPARISONOPERATORANYOF_LTE ComparisonOperatorAnyOf = "LTE"
)`

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[kemokemo]

@pmcgleenon
Thank you so much for your PR!
A short review was conducted. LGTM. ( related #7008 )

[pmcgleenon]

@kemokemo Thanks for the quick feedback!

[wing328]

@pmcgleenon thanks for the PR, which has been included in the v5.1.0 release: https://twitter.com/oas_generator/status/1373636654024380423