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.

cdc_rsync/protos/BUILD

@@ -0,0 +1,14 @@
+package(default_visibility = [
+    "//:__subpackages__",
+])
+
+proto_library(
+    name = "messages_proto",
+    srcs = ["messages.proto"],
+    visibility = ["//visibility:private"],
+)
+
+cc_proto_library(
+    name = "messages_cc_proto",
+    deps = [":messages_proto"],
+)