[Improvement] Naming of libraries and package (#22)

This PR contains the work done to fix the naming of the libraries and the package, along with tweaks to the folder structure.

Reviewed-on: #22
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Libraries/Persistence/Protocols/Service.swift

@@ -0,0 +1,42 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftLibs open source project
+//
+// Copyright (c) 2023 Röck+Cöde VoF. and the SwiftLibs project authors
+// Licensed under the EUPL 1.2 or later.
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftLibs project authors
+//
+//===----------------------------------------------------------------------===//
+
+#if canImport(CoreData)
+import CoreData
+
+public protocol Service {
+    
+    // MARK: Properties
+    
+    /// The main managed object context.
+    var viewContext: NSManagedObjectContext { get }
+    
+    // MARK: Functions
+    
+    /// Create a private queue context.
+    /// - Returns: A concurrent `NSManagedObjectContext` context instance ready to use.
+    func makeTaskContext() -> NSManagedObjectContext
+    
+    /// Create a child context of the view context.
+    /// - Returns: A generated child `NSManagedObjectContext` context instance ready to use.
+    func makeChildContext() -> NSManagedObjectContext
+    
+    /// Save a given context.
+    /// - Parameter context: A `NSManagedObjectContext` context instance to save.
+    func save(context: NSManagedObjectContext) throws
+    
+    /// Save a given child context as well as its respective parent context.
+    /// - Parameter context: A child `NSManagedObjectContext` context instance to save.
+    func save(childContext context: NSManagedObjectContext) throws 
+    
+}
+#endif