Update "Add package" button text on the Saved screen

The text on the "Add package" button in the `WooShippingSavedPackageScreen`
is updated to display "Select a Package" when the button is disabled.

Author: irfano

WooCommerce/src/main/kotlin/com/woocommerce/android/ui/orders/wooshippinglabels/packages/ui/WooShippingSavedPackageScreen.kt

@@ -103,7 +103,15 @@ fun WooShippingSavedPackageScreen(
             enabled = isAddPackageEnabled,
             onClick = onAddPackageClick
         ) {
-            Text(stringResource(id = R.string.woo_shipping_labels_package_creation_add_package))
+            Text(
+                stringResource(
+                    id = if (isAddPackageEnabled) {
+                        R.string.woo_shipping_labels_package_creation_add_package
+                    } else {
+                        R.string.shipping_label_select_package_button
+                    }
+                )
+            )
         }
     }
 }