[Feature] add json to go converter and generating return values

[akinsho]

Hi 👋🏿

I recently watched the author of go.nvim's video on YT about new features. Two struck out to me as being good candidates to be added here that might be useful

• Converting json to go structs
• Generating the return values for a function (originally inspired by a goland feature)

[olexsmir]

Hi! 👋

1. About adding the JSON to Go struct converter, I think about it many times, and I'll add that in the future!
2. About the "return generator" I don't know, but If you need that I can try to add that.

Thanks for feature request!

[vitorf7]

If maybe a package like this had a CLI that we could install it would definitely be helpful