Patched (temporarily) the DocC documentation (#8)

This PR contains the work done to:
* Documented the public properties, initializers, and/or functions of those types conforming to the `APIClient`, `KeyNameFilter`, and `KeyNameModel` protocols, to fix the issue that the protocol documentations cannot be inherited;
* Moved the `AmiiboService` DocC documentation catalog inside the library target;
* Amended the folder structure of the library and test targets;
* Fixed further documentation issues encountered while revising the written documentation;
* Added the `lib-test` task in the `Makefile` file;
* Improved the naming for the existing tasks in the `Makefile` file.

Reviewed-on: #8
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Sources/AmiiboService/Public/Models/GameCharacter.swift

@@ -0,0 +1,33 @@
+//===----------------------------------------------------------------------===
+//
+// This source file is part of the AmiiboService open source project
+//
+// Copyright (c) 2024-2025 Röck+Cöde VoF. and the AmiiboAPI project authors
+// Licensed under the EUPL 1.2 or later.
+//
+// See LICENSE for license information
+// See CONTRIBUTORS for the list of AmiiboAPI project authors
+//
+//===----------------------------------------------------------------------===
+
+/// A model that represents a game character.
+public struct GameCharacter: KeyNameModel {
+
+    // TODO: Remove the documentation from the properties of this type as the `--enable-inherited-docs` flag when generating DocC documentation is not working as intended (?).
+
+    // MARK: Properties
+
+    /// A key.
+    public let key: String
+
+    /// A name.
+    public let name: String
+    
+    // MARK: Initializers
+    
+    init(_ payload: Components.Schemas.Tuple) {
+        self.key = payload.key
+        self.name = payload.name
+    }
+    
+}