feat: add insertion point for typedef

[wolfogre]

Description

Add an insertion point for typedef to provide convenience for plugins that add some stuff for typedef.

Motivation and Context

I built a plugin to support string enums, it works like

typedef string Person (
  datatype = "enum",
  datatype.enum.john = "john",
  datatype.enum.mary = "mary",
  datatype.enum.jack = "jack",
)

thriftgo -g go:use_type_alias=false,no_default_serdes -plugin datatype <path-to-thrift-file>

type Person string

const (
	PersonJohn Person = "john"
	PersonMary Person = "mary"
	PersonJack Person = "jack"
)

func (v Person) IsValid() error {
	switch v {
	case PersonJohn:
		return nil
	case PersonMary:
		return nil
	case PersonJack:
		return nil
	default:
		return fmt.Errorf("invalid Person: %q", v)
	}
}

func PersonList() []Person {
	return []Person{
		PersonJohn,
		PersonMary,
		PersonJack,
	}
}

It works well; however, there's no InsertionPoint in the template for typedef, so I have to use the eof point, which makes the generated code hard to read: the additional code is far away from the definition of the type. 😢

Related Issue

None.

[HeyJavaBean]

Thanks for your contribution. I understand your case, but I don't think it's necessary😢. Adding a new insertion point doesn't solve bugs or bring new features, just for code format, so I think the complexity it introduces outweighs the benefits.

[wolfogre]

@HeyJavaBean Thank you for your explanation.

However, I earnestly request a reconsideration of this.

Many other templates have one or more insertion points of their own.

thriftgo/generator/golang/templates/constant.go

Line 24 in 9bb03d9

{{InsertionPoint "constant" .Name}}

thriftgo/generator/golang/templates/enum.go

Line 21 in 9bb03d9

{{InsertionPoint "enum" .Name}}

thriftgo/generator/golang/templates/service.go

Line 47 in 9bb03d9

{{InsertionPoint "service" .Name}}

All of them are valuable, right?

So does typedef also deserve to have one just like them?

[HeyJavaBean]

ok

[wolfogre]

@HeyJavaBean Thanks for reconsidering and merging this!