Reorder fullfillment errors to keep more interesting ones first

In `report_fullfillment_errors` push back `T: Sized`, `T: WellFormed`
and coercion errors to the end of the list. The pre-existing
deduplication logic eliminates redundant errors better that way, keeping
the resulting output with fewer errors than before, while also having
more detail.

compiler/rustc_trait_selection/src/traits/engine.rs

@@ -218,7 +218,7 @@ impl<'a, 'tcx> ObligationCtxt<'a, 'tcx> {
         def_id: LocalDefId,
     ) -> Result<FxIndexSet<Ty<'tcx>>, ErrorGuaranteed> {
         self.assumed_wf_types(param_env, def_id)
-            .map_err(|errors| self.infcx.err_ctxt().report_fulfillment_errors(&errors))
+            .map_err(|errors| self.infcx.err_ctxt().report_fulfillment_errors(errors))
     }
 
     pub fn assumed_wf_types(