[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.

cdc_stream/BUILD

@@ -0,0 +1,26 @@
+package(default_visibility = [
+    "//:__subpackages__",
+])
+
+cc_binary(
+    name = "cdc_stream",
+    srcs = ["main.cc"],
+    deps = [
+        ":local_assets_stream_manager_client",
+        "//common:log",
+        "//common:path",
+        "@com_google_absl//absl/flags:parse",
+        "@com_google_absl//absl/status",
+    ],
+)
+
+cc_library(
+    name = "local_assets_stream_manager_client",
+    srcs = ["local_assets_stream_manager_client.cc"],
+    hdrs = ["local_assets_stream_manager_client.h"],
+    deps = [
+        "//common:grpc_status",
+        "//proto:local_assets_stream_manager_grpc_proto",
+        "@com_google_absl//absl/status",
+    ],
+)