Implemented Windows implementation compliant Linux http_loader

The `http_loader` class takes a `WebRequest` with information to send a
web request, and sends it. This uses `libcurl`, which is present from
installation on most major Linux distrobutions (e.g. Fedora, Ubuntu,
PopOS...).

If libcurl is not present on the target system, it will need to be
installed.

internal/platform/implementation/linux/http_loader_test.cc

@@ -0,0 +1,51 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "internal/platform/implementation/linux/http_loader.h"
+
+#include <string>
+
+#include "gtest/gtest.h"
+
+namespace nearby {
+namespace linux {
+namespace {
+using ::nearby::api::WebRequest;
+
+TEST(HttpLoader, DISABLED_TestGetUrl) {
+  WebRequest request;
+  request.url = "https://www.google.com?id=456#fragment";
+  request.method = "GET";
+  auto response = HttpLoader(request).GetResponse();
+  ASSERT_TRUE(response.ok());
+  EXPECT_EQ(response->status_code, 200);
+}
+
+TEST(HttpLoader, DISABLED_TestGetNotExistingUrl) {
+  WebRequest request;
+  request.url = "https://www.abcdefgabcdefg.com";
+  request.method = "GET";
+  EXPECT_FALSE(HttpLoader(request).GetResponse().ok());
+}
+
+TEST(HttpLoader, DISABLED_TestInvalidUrl) {
+  WebRequest request;
+  request.url = "https:/www.abcdefgabcdefg.com/name?id=456";
+  request.method = "GET";
+  EXPECT_FALSE(HttpLoader(request).GetResponse().ok());
+}
+
+}  // namespace
+}  // namespace linux
+}  // namespace nearby