Add OrderedDict. Refactor Dict.render to utilize OrderedDict

[rainforest-bailey]

I would like to add a companion type to 'Dict', an 'OrderedDict', that will retain original ordering on keys.

[rainforest-bailey]

For additional context on why this feature is useful. When generating code to initialize a struct, it is beneficial to be able to control the order in which fields are defined. I found myself comparing my code gen to an existing spec definition. Ideally, I would be able to visually scan the 2 side by side, but I had to search each field individually, which was more cumbersome.

[dave]

When creating a struct definition, you don't need to use Dict... the Struct method preserves the order of items:

c := Type().Id("foo").Struct(
	List(Id("x"), Id("y")).Int(),
	Id("u").Float32(),
)
fmt.Printf("%#v", c)
// Output:
// type foo struct {
// 	x, y int
// 	u    float32
// }

See https://github.com/dave/jennifer?tab=readme-ov-file#interface-struct

[rainforest-bailey]

@dave How would I initialize a struct with a defined field ordering?

[dave]

Can you show me the code you want it to output?