Move #[godot_dyn] code generation to its own function

[ValorZard]

lets start with something small for now

[ValorZard]

Forgot to mention that this is Part 1 of #1231

[ValorZard]

(how do i switch this back to WIP?)

[Yarwin]

(how do i switch this back to WIP?)

It is kind of non intuitive, there is an option to do that under "Reviewers"

[GodotRust]

API docs are being generated and will be shortly available at: https://godot-rust.github.io/docs/gdext/pr-1235

[Bromeon]

@ValorZard what's the status on this? As mentioned in #1231 (comment), it would likely be better to allow #[func] in the trait definition, rather than the impl. Would you still be interested in pursuing a PR under these circumstances? Do you need concrete help?

Also, would be good to keep the refactoring to a minimum -- for example, moving around functions like transform_dyn_trait_impl creates a large diff and makes it hard to see if something changed during the move. If you're interested in changing code structure, we can do a follow-up PR for just that, but it's usually better to not mix new features with larger refactors.

[ValorZard]

I’ll close the PR for now. I think the way I went about this is wrong since I think the #[func] definitions should exist in the trait itself instead of the implementation.

I am currently busy with other projects, but If I do come back to this PR, I’d probably look into implementing some sort of #[godot_trait] macro for traits