Group tasks feature (#3)

This PR contains the work done to implement the **Group Task** feature, and to integrate it into the main content view of the app. Furthermore, an issue related to triggering a view update after inserting the todo tasks into the model container has been fixed.

Reviewed-on: rock-n-code/todos-app#3
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

App/Resources/Localizable.xcstrings

@@ -1,6 +1,50 @@
 {
   "sourceLanguage" : "en",
   "strings" : {
+    "enumeration.todo-group.title.completed" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Completed"
+          }
+        }
+      }
+    },
+    "enumeration.todo-group.title.overdue" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Overdue"
+          }
+        }
+      }
+    },
+    "enumeration.todo-group.title.today" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Today"
+          }
+        }
+      }
+    },
+    "enumeration.todo-group.title.upcoming" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Upcoming"
+          }
+        }
+      }
+    },
     "view.new-task.navigation.title" : {
       "extractionState" : "manual",
       "localizations" : {
@@ -66,6 +110,17 @@
           }
         }
       }
+    },
+    "view.task-group-list.navigation.title" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Todos"
+          }
+        }
+      }
     }
   },
   "version" : "1.1"