Rename pallet trait Trait to Config (#7599)

* rename Trait to Config

* add test asserting using Trait is still valid.

* fix ui tests

substrate/primitives/runtime/src/traits.rs

@@ -693,7 +693,7 @@ pub trait Dispatchable {
 	/// identifier for the caller. The origin can be empty in the case of an inherent extrinsic.
 	type Origin;
 	/// ...
-	type Trait;
+	type Config;
 	/// An opaque set of information attached to the transaction. This could be constructed anywhere
 	/// down the line in a runtime. The current Substrate runtime uses a struct with the same name
 	/// to represent the dispatch class and weight.
@@ -712,7 +712,7 @@ pub type PostDispatchInfoOf<T> = <T as Dispatchable>::PostInfo;
 
 impl Dispatchable for () {
 	type Origin = ();
-	type Trait = ();
+	type Config = ();
 	type Info = ();
 	type PostInfo = ();
 	fn dispatch(self, _origin: Self::Origin) -> crate::DispatchResultWithInfo<Self::PostInfo> {