[swift 4] improve test suite (#4561)

* [swift] improve testing in sample projects

* [swift] update run tests script

* [swift] regenerate samples

* [swift] fix tests with PromiseKit

* [swift4] compile every project with swift package manager

samples/client/petstore/swift4/rxswiftLibrary/Package.swift

@@ -0,0 +1,28 @@
+// swift-tools-version:4.2
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "PetstoreClient",
+    products: [
+        // Products define the executables and libraries produced by a package, and make them visible to other packages.
+        .library(
+            name: "PetstoreClient",
+            targets: ["PetstoreClient"])
+    ],
+    dependencies: [
+        // Dependencies declare other packages that this package depends on.
+        .package(url: "https://github.com/Alamofire/Alamofire.git", from: "4.9.0"),
+        .package(url: "https://github.com/ReactiveX/RxSwift.git", from: "4.5.0")
+    ],
+    targets: [
+        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
+        // Targets can depend on other targets in this package, and on products in packages which this package depends on.
+        .target(
+            name: "PetstoreClient",
+            dependencies: ["Alamofire", "RxSwift"],
+            path: "PetstoreClient/Classes"
+        )
+    ]
+)