Updated examples/layers to use the new button API. (#62932)

Updated examples/layers to use the new button API.

examples/layers/services/isolate.dart

@@ -253,7 +253,7 @@ class IsolateExampleState extends State<StatefulWidget> with SingleTickerProvide
           ),
           Text(_status),
           Center(
-            child: RaisedButton(
+            child: ElevatedButton(
               child: Text(_label),
               onPressed: _handleButtonPressed,
             ),

examples/layers/widgets/sectors.dart

@@ -96,7 +96,7 @@ class SectorAppState extends State<SectorApp> {
           padding: const EdgeInsets.symmetric(horizontal: 8.0, vertical: 25.0),
           child: Row(
             children: <Widget>[
-              RaisedButton(
+              ElevatedButton(
                 onPressed: _enabledAdd ? addSector : null,
                 child: IntrinsicWidth(
                   child: Row(
@@ -111,7 +111,7 @@ class SectorAppState extends State<SectorApp> {
                   ),
                 ),
               ),
-              RaisedButton(
+              ElevatedButton(
                 onPressed: _enabledRemove ? removeSector : null,
                 child: IntrinsicWidth(
                   child: Row(