Add HoldReason to the NIS pallet (#13823)

* Add HoldReason to the NIS pallet

* Rename composable_enum to composite_enum

* Add encoding test

* Add more doc comments

substrate/frame/support/procedural/src/construct_runtime/expand/freeze_reason.rs

@@ -35,6 +35,7 @@ pub fn expand_outer_freeze_reason(pallet_decls: &[Pallet], scrate: &TokenStream)
 	}
 
 	quote! {
+		/// A reason for placing a freeze on funds.
 		#[derive(
 			Copy, Clone, Eq, PartialEq, Ord, PartialOrd,
 			#scrate::codec::Encode, #scrate::codec::Decode, #scrate::codec::MaxEncodedLen,

substrate/frame/support/procedural/src/construct_runtime/expand/hold_reason.rs

@@ -35,6 +35,7 @@ pub fn expand_outer_hold_reason(pallet_decls: &[Pallet], scrate: &TokenStream) -
 	}
 
 	quote! {
+		/// A reason for placing a hold on funds.
 		#[derive(
 			Copy, Clone, Eq, PartialEq, Ord, PartialOrd,
 			#scrate::codec::Encode, #scrate::codec::Decode, #scrate::codec::MaxEncodedLen,

substrate/frame/support/procedural/src/construct_runtime/expand/lock_id.rs

@@ -35,6 +35,7 @@ pub fn expand_outer_lock_id(pallet_decls: &[Pallet], scrate: &TokenStream) -> To
 	}
 
 	quote! {
+		/// An identifier for each lock placed on funds.
 		#[derive(
 			Copy, Clone, Eq, PartialEq, Ord, PartialOrd,
 			#scrate::codec::Encode, #scrate::codec::Decode, #scrate::codec::MaxEncodedLen,

substrate/frame/support/procedural/src/construct_runtime/expand/slash_reason.rs

@@ -35,6 +35,7 @@ pub fn expand_outer_slash_reason(pallet_decls: &[Pallet], scrate: &TokenStream)
 	}
 
 	quote! {
+		/// A reason for slashing funds.
 		#[derive(
 			Copy, Clone, Eq, PartialEq, Ord, PartialOrd,
 			#scrate::codec::Encode, #scrate::codec::Decode, #scrate::codec::MaxEncodedLen,