[Enhancement] Communications library for non Apple platforms (#15)

This PR contains the work done to allow the `MakeURLRequestUseCase` use case to be used in non-Apple platforms, as it use has been restricted before.

To provide further details about the work done:
- [x] improved the `MakeURLRequestUseCase` use case to be available in non-Apple platforms;
- [x] moved the `TestEndpoint` helper endpoint to its own file;
- [x] moved some test cases files around;
- [x] updated some text in the `README` file.

Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Reviewed-on: #15

Tests/Communications/Cases/Use Cases/MakeURLRequestUseCaseTests.swift

@@ -10,11 +10,14 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if os(iOS) || os(macOS) || os(tvOS) || os(watchOS)
 import Communications
 import Foundation
 import XCTest
 
+#if canImport(FoundationNetworking)
+import FoundationNetworking
+#endif
+
 final class MakeURLRequestUseCaseTests: XCTestCase {
 
     // MARK: Properties
@@ -111,35 +114,3 @@ final class MakeURLRequestUseCaseTests: XCTestCase {
     }
 
 }
-
-// MARK: - TestEndpoint
-
-private struct TestEndpoint: Endpoint {
-
-    // MARK: Properties
-    
-    let scheme: String = "http"
-    let host: String = "www.something.com"
-    let port: Int?
-    let path: String = "/path/to/endpoint"
-    let parameters: Parameters
-    let method: HTTPRequestMethod = .get
-    let headers: Headers
-    let body: Data?
-
-    // MARK: Initialisers
-    
-    init(
-        port: Int? = nil,
-        parameters: Parameters = [:],
-        headers: Headers = [:],
-        body: Data? = nil
-    ) {
-        self.port = port
-        self.parameters = parameters
-        self.headers = headers
-        self.body = body
-    }
-
-}
-#endif