[cdc_stream] Add a CLI client to start/stop asset streaming sessions (#4)

Implements the cdc_stream client and adjusts asset streaming in
various places to work better outside of a GGP environment.

This CL tries to get quoting for SSH commands right. It also brings
back the ability to start a streaming session from
asset_stream_manager.

Also cleans up Bazel targets setup. Since the sln file is now in root,
it is no longer necessary to prepend ../ to relative filenames to
make clicking on errors work.

common/path.cc

@@ -326,6 +326,10 @@ std::string GetDrivePrefix(const std::string& path) {
 
 std::string GetCwd() { return std::filesystem::current_path().u8string(); }
 
+void SetCwd(const std::string& path) {
+  std::filesystem::current_path(std::filesystem::u8path(path));
+}
+
 std::string GetFullPath(const std::string& path) {
   if (path.empty()) {
     return std::string();