Implement http-module (#637)

Create http-module and implement it in App Hub and App Hub Details apps.

Modules/http-module/source/download_mock.cpp

@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: Apache-2.0
+#include <http/private/download.h>
+
+HttpDownloadEvent http_download_run(const std::string&, const std::string&, const std::string&, HttpDownloadLink* link) {
+    if (http_download_is_cancelled(link)) {
+        return http_download_make_cancelled_event();
+    }
+    return http_download_make_error_event("HTTP downloads are not supported on this platform");
+}