Derive TypeInfo for fields with associated types without bounds

[ascjones]

WIP, copied and amended trait_bounds from parity_scale_codec. Works but needs refactoring and documenting.

e.g.

trait Types {
	type A; // doesn't require TypeInfo trait bound
}
#[derive(TypeInfo)]
struct Assoc<T: Types> {
	a: T::A 
}

#[derive(TypeInfo)]
enum ConcreteTypes {}
impl Types for ConcreteTypes {
	type A = bool;
}

This generates a TypeInfo impl with bounds on the associated types i.e.

impl<T> for Assoc<T> where T: Types, T::A: TypeInfo

[dvdplm]

Looks like this is in a pretty good state? What is still outstanding here, docs and that todo?

[ascjones]

Ooh thanks for pinging this. Yeah just the things you specified there and syncing with master

[ascjones]

LGTM

[dvdplm]

Approval by proxy