Releasing the former Stadia file transfer tools

The tools allow efficient and fast synchronization of large directory
trees from a Windows workstation to a Linux target machine.

cdc_rsync* support efficient copy of files by using content-defined
chunking (CDC) to identify chunks within files that can be reused.

asset_stream_manager + cdc_fuse_fs support efficient streaming of a
local directory to a remote virtual file system based on FUSE. It also
employs CDC to identify and reuse unchanged data chunks.

common/test_main.h

@@ -0,0 +1,32 @@
+/*
+ * 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
+ *
+ *      http://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.
+ */
+
+#ifndef COMMON_TEST_MAIN_H_
+#define COMMON_TEST_MAIN_H_
+
+#include <string>
+
+namespace cdc_ft {
+
+// Retreives the full path of the testdata/|test_data_dir| directory from
+// runfiles. The testdata directory must have an empty file named "root.txt".
+// |test_data_dir| usually matches the filename of the test file without the
+// trailing "_test.cc", e.g. "path" for "path_test.cc".
+std::string GetTestDataDir(const char* test_data_dir);
+
+}  // namespace cdc_ft
+
+#endif  // COMMON_TEST_MAIN_H_