Add new string consts

lib/consts.dart

@@ -423,7 +423,10 @@ const kRaiseIssue =
     "\nPlease raise an issue in API Dash GitHub repo so that we can resolve it.";
 
 const kHintTextUrlCard = "Enter API endpoint like api.foss42.com/country/codes";
+const kLabelPlusNew = "+ New";
 const kLabelSend = "Send";
 const kLabelSending = "Sending..";
 const kLabelBusy = "Busy";
 const kLabelCopy = "Copy";
+const kLabelSave = "Save";
+const kLabelDownload = "Download";

lib/screens/home_page/collection_pane.dart

@@ -75,7 +75,7 @@ class _CollectionPaneState extends ConsumerState<CollectionPane> {
                   size: 20,
                 ),
                 label: const Text(
-                  'Save',
+                  kLabelSave,
                   style: kTextStyleButton,
                 ),
               ),
@@ -89,7 +89,7 @@ class _CollectionPaneState extends ConsumerState<CollectionPane> {
                       .update((state) => newId);
                 },
                 child: const Text(
-                  '+ New',
+                  kLabelPlusNew,
                   style: kTextStyleButton,
                 ),
               ),

lib/widgets/intro_message.dart

@@ -106,7 +106,7 @@ class _IntroMessageState extends State<IntroMessage> {
                         child: ElevatedButton(
                           onPressed: widget.onNew,
                           child: const Text(
-                            '+ New',
+                            kLabelPlusNew,
                             style: kTextStyleButton,
                           ),
                         ),