Enforce use_key_in_widget_constructors and file_names lints (#913)

* Start enforcing use_key_in_widget_constructors and file_names lints

* dart format

* analysis fixes

* analysis fixes, pt2

* analysis fixes, part 3

* Revert platform_design (test failure)

* More reverts

* Notate why we aren't enforcing a lint

veggieseasons/lib/main.dart

@@ -18,7 +18,7 @@ void main() {
   ]);
 
   runApp(
-    RootRestorationScope(
+    const RootRestorationScope(
       restorationId: 'root',
       child: VeggieApp(),
     ),
@@ -26,6 +26,8 @@ void main() {
 }
 
 class VeggieApp extends StatefulWidget {
+  const VeggieApp({Key key}) : super(key: key);
+
   @override
   State<StatefulWidget> createState() => _VeggieAppState();
 }

veggieseasons/lib/screens/details.dart

@@ -13,7 +13,7 @@ import 'package:veggieseasons/widgets/close_button.dart';
 import 'package:veggieseasons/widgets/trivia.dart';
 
 class ServingInfoChart extends StatelessWidget {
-  const ServingInfoChart(this.veggie, this.prefs);
+  const ServingInfoChart(this.veggie, this.prefs, {Key key}) : super(key: key);
 
   final Veggie veggie;
 
@@ -158,7 +158,7 @@ class ServingInfoChart extends StatelessWidget {
 class InfoView extends StatelessWidget {
   final int id;
 
-  const InfoView(this.id);
+  const InfoView(this.id, {Key key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -239,7 +239,7 @@ class DetailsScreen extends StatefulWidget {
   final int id;
   final String restorationId;
 
-  const DetailsScreen({this.id, this.restorationId});
+  const DetailsScreen({this.id, this.restorationId, Key key}) : super(key: key);
 
   static String show(NavigatorState navigator, int veggieId) {
     return navigator.restorablePush<void>(_routeBuilder, arguments: veggieId);

veggieseasons/lib/widgets/close_button.dart

@@ -80,7 +80,7 @@ class _ColorChangingIconState
 
 /// A simple "close this modal" button that invokes a callback when pressed.
 class CloseButton extends StatefulWidget {
-  const CloseButton(this.onPressed);
+  const CloseButton(this.onPressed, {Key key}) : super(key: key);
 
   final VoidCallback onPressed;
 

veggieseasons/lib/widgets/settings_group.dart

@@ -14,7 +14,7 @@ import 'settings_item.dart';
 // See https://github.com/flutter/flutter/projects/29 for more info.
 
 class SettingsGroupHeader extends StatelessWidget {
-  const SettingsGroupHeader(this.title);
+  const SettingsGroupHeader(this.title, {Key key}) : super(key: key);
 
   final String title;
 
@@ -35,7 +35,7 @@ class SettingsGroupHeader extends StatelessWidget {
 }
 
 class SettingsGroupFooter extends StatelessWidget {
-  const SettingsGroupFooter(this.title);
+  const SettingsGroupFooter(this.title, {Key key}) : super(key: key);
 
   final String title;
 
@@ -58,8 +58,10 @@ class SettingsGroup extends StatelessWidget {
     @required this.items,
     this.header,
     this.footer,
+    Key key,
   })  : assert(items != null),
-        assert(items.isNotEmpty);
+        assert(items.isNotEmpty),
+        super(key: key);
 
   final List<SettingsItem> items;
   final Widget header;

veggieseasons/lib/widgets/trivia.dart

@@ -11,7 +11,7 @@ class TriviaView extends StatefulWidget {
   final int id;
   final String restorationId;
 
-  const TriviaView({this.id, this.restorationId});
+  const TriviaView({this.id, this.restorationId, Key key}) : super(key: key);
 
   @override
   _TriviaViewState createState() => _TriviaViewState();

veggieseasons/lib/widgets/veggie_card.dart

@@ -14,7 +14,8 @@ class FrostyBackground extends StatelessWidget {
     this.color,
     this.intensity = 25,
     this.child,
-  });
+    Key key,
+  }) : super(key: key);
 
   final Color color;
   final double intensity;
@@ -105,7 +106,9 @@ class _PressableCardState extends State<PressableCard> {
 }
 
 class VeggieCard extends StatelessWidget {
-  const VeggieCard(this.veggie, this.isInSeason, this.isPreferredCategory);
+  const VeggieCard(this.veggie, this.isInSeason, this.isPreferredCategory,
+      {Key key})
+      : super(key: key);
 
   /// Veggie to be displayed by the card.
   final Veggie veggie;

veggieseasons/lib/widgets/veggie_headline.dart

@@ -12,7 +12,9 @@ class ZoomClipAssetImage extends StatelessWidget {
       {@required this.zoom,
       this.height,
       this.width,
-      @required this.imageAsset});
+      @required this.imageAsset,
+      Key key})
+      : super(key: key);
 
   final double zoom;
   final double height;
@@ -43,7 +45,7 @@ class ZoomClipAssetImage extends StatelessWidget {
 class VeggieHeadline extends StatelessWidget {
   final Veggie veggie;
 
-  const VeggieHeadline(this.veggie);
+  const VeggieHeadline(this.veggie, {Key key}) : super(key: key);
 
   List<Widget> _buildSeasonDots(List<Season> seasons) {
     var widgets = <Widget>[];