Basic application setup (#1)

This PR contains the work done to define the necessary setup from which the app will be built upon.

To provide further details on what has been done:
* created the app, the unit tests and the UI tests targets in the Xcode project;
* updated the bundle identifiers and OS deployment targets of all targets;
* added a `.gitignore` file tailored specifically for the project;
* added a `README` file that defines in details the goal of the project;
* added the [Swift Format](https://github.com/swiftlang/swift-format) rules that the source code should abide to;
* cleaned the boilerplate source code on all targets.

Reviewed-on: rock-n-code/todos-app#1
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

UITests/TodosUITests.swift

@@ -0,0 +1,34 @@
+import XCTest
+
+final class TodosUITests: XCTestCase {
+
+    override func setUpWithError() throws {
+        // Put setup code here. This method is called before the invocation of each test method in the class.
+
+        // In UI tests it is usually best to stop immediately when a failure occurs.
+        continueAfterFailure = false
+
+        // In UI tests it’s important to set the initial state - such as interface orientation - required for your tests before they run. The setUp method is a good place to do this.
+    }
+
+    override func tearDownWithError() throws {
+        // Put teardown code here. This method is called after the invocation of each test method in the class.
+    }
+
+    @MainActor
+    func testExample() throws {
+        // UI tests must launch the application that they test.
+        let app = XCUIApplication()
+        app.launch()
+
+        // Use XCTAssert and related functions to verify your tests produce the correct results.
+    }
+
+    @MainActor
+    func testLaunchPerformance() throws {
+        // This measures how long it takes to launch your application.
+        measure(metrics: [XCTApplicationLaunchMetric()]) {
+            XCUIApplication().launch()
+        }
+    }
+}