Task deletion feature (#7)

This PR contains the work done to add support for todo tasks deletion on the *Task list* view.

Reviewed-on: rock-n-code/todos-app#7
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

UnitTests/Tests/View Models/TaskListViewModelTests.swift

@@ -91,6 +91,45 @@ struct TaskListViewModelTests {
 
     // MARK: Method tests
 
+    @Test("deleteTasks removes a single task from model context")
+    func deleteTasksSingle() throws {
+        // GIVEN
+        let container = try ModelContainer(
+            for: Todo.self,
+            configurations: .init(isStoredInMemoryOnly: true)
+        )
+        let context = ModelContext(container)
+
+        let viewModel = TaskListView.ViewModel(group: .today)
+        let todosToInsert: [Todo] = [
+            .init(title: "Task 1", due: .now, order: 0),
+            .init(title: "Task 2", due: .now, order: 1),
+            .init(title: "Task 3", due: .now, order: 2),
+        ]
+        let countInitial = todosToInsert.count
+
+        for todo in todosToInsert {
+            context.insert(todo)
+        }
+
+        // WHEN
+        viewModel.deleteTasks(
+            todosToInsert,
+            at: IndexSet(integer: 1),
+            from: context
+        )
+
+        // THEN
+        let descriptor = FetchDescriptor<Todo>()
+        let todos = try context.fetch(descriptor)
+
+        #expect(countInitial == 3)
+        #expect(todos.count == 2)
+        #expect(todos.contains(where: { $0.title == "Task 1" }))
+        #expect(todos.contains(where: { $0.title == "Task 3" }))
+        #expect(!todos.contains(where: { $0.title == "Task 2" }))
+    }
+
     @Test("reorderTasks updates order property when moving task forward")
     func reorderTasksMovingForward() {
         // GIVEN