Stabilize seal_debug_message (#9550)

* Stableize `seal_debug_message`

* Update changelog

* Enable more tests

* Cargo fmt

substrate/primitives/npos-elections/solution-type/src/lib.rs

@@ -79,7 +79,7 @@ pub(crate) fn syn_err(message: &'static str) -> syn::Error {
 /// 			(u8 /* first target*/, Perbill /* proportion for first target */ ),
 /// 			(u8 /* second target */, Perbill /* proportion for second target*/)
 /// 		], u8 /* last target */)
-///		],
+/// 		],
 /// 	voters4: ...,
 /// }
 ///