Issue 1812: adds support for complex types with function scope

[KristofferFJ]

Describe the PR
Building on top of: #1283
Further support for function scoped types, we will now be able to define more complex request and responses in a function scope:

package main

// @Param request body main.Fun.request true "query params" 
// @Success 200 {object} main.Fun.response
// @Router /test [post]
func Fun()  {
	type request struct {
		Name string
	}
	
        type child struct {
                Name string
        }

	type response struct {
		Child child
	}
}

Relation issue
e.g. https://github.com/swaggo/swag/pull/118/files

Additional context
I do not have a lot of experience with this project, so any input is more than welcome.

[KristofferFJ]

@ubogdan
Any chance you have some time to take a look at this?