Refactored file upload: generalized HttpGatewayAcceptor file-download

Author: artem-v

services-gateway/src/test/java/io/scalecube/services/gateway/files/FileDownloadTest.java

@@ -124,7 +124,7 @@ void afterEach() {
   class FileServiceTests {
 
     @ParameterizedTest(name = "Download file of size {0} bytes")
-    @ValueSource(longs = {512, 1024, 1024 * 1024, 10 * 1024 * 1024})
+    @ValueSource(longs = {0, 512, 1024, 1024 * 1024, 10 * 1024 * 1024})
     void testDownloadSuccessfully(long fileSize) throws Exception {
       final var reportResponse =
           serviceCall
@@ -307,7 +307,7 @@ void failOnDownload(String path) {
     }
 
     @ParameterizedTest(name = "Download file of size {0} bytes")
-    @ValueSource(longs = {0, 64, 512, 1024, 1024 * 1024, 10 * 1024 * 1024})
+    @ValueSource(longs = {0, 512, 1024, 1024 * 1024, 10 * 1024 * 1024})
     void successfulDownload(long fileSize) throws Exception {
       final var file =
           downloadFile(