[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/promisekitLibrary/docs/AnotherFakeAPI.md

@@ -0,0 +1,56 @@
+# AnotherFakeAPI
+
+All URIs are relative to *http://petstore.swagger.io:80/v2*
+
+Method | HTTP request | Description
+------------- | ------------- | -------------
+[**call123testSpecialTags**](AnotherFakeAPI.md#call123testspecialtags) | **PATCH** /another-fake/dummy | To test special tags
+
+
+# **call123testSpecialTags**
+```swift
+    open class func call123testSpecialTags( body: Client) -> Promise<Client>
+```
+
+To test special tags
+
+To test special tags and operation ID starting with number
+
+### Example 
+```swift
+// The following code samples are still beta. For any issue, please report via http://github.com/OpenAPITools/openapi-generator/issues/new
+import PetstoreClient
+
+let body = Client(client: "client_example") // Client | client model
+
+// To test special tags
+AnotherFakeAPI.call123testSpecialTags(body: body).then {
+         // when the promise is fulfilled
+     }.always {
+         // regardless of whether the promise is fulfilled, or rejected
+     }.catch { errorType in
+         // when the promise is rejected
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **body** | [**Client**](Client.md) | client model | 
+
+### Return type
+
+[**Client**](Client.md)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: application/json
+ - **Accept**: application/json
+
+[[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
+