Rollup merge of #76995 - LingMan:middle_matches, r=varkor

Reduce boilerplate with the matches! macro

Replaces simple bool `match`es of the form

    match $expr {
        $pattern => true
        _ => false
    }

and their inverse with invocations of the matches! macro.

Limited to rustc_middle for now to get my feet wet.

compiler/rustc_middle/src/ty/instance.rs

@@ -184,10 +184,10 @@ impl<'tcx> InstanceDef<'tcx> {
             ty::InstanceDef::DropGlue(_, Some(_)) => return false,
             _ => return true,
         };
-        match tcx.def_key(def_id).disambiguated_data.data {
-            DefPathData::Ctor | DefPathData::ClosureExpr => true,
-            _ => false,
-        }
+        matches!(
+            tcx.def_key(def_id).disambiguated_data.data,
+            DefPathData::Ctor | DefPathData::ClosureExpr
+        )
     }
 
     /// Returns `true` if the machine code for this instance is instantiated in