Specify widevine/media_cas_packager_sdk/presubmit in media_cas_packager_sdk METADATA file.

-------------
Moves ecm_generator to media_cas_packager_sdk/internal.

-------------
Add a simple TCP server listening on a port. My intention is to use this server to support the Simulcrypt APIs (TODO).

Also add a simple TCP client binary for testing the server and also demo how to call the Simulcrypt APIs (TODO).

-------------
If only a single key is in the ECM, it is the EVEN key. To make the code matches this understanding, change a parameter from 'false' to 'true'. But this change has NO impact on the produced ECM, regardless this parameter is 'false' or 'true' (i.e., whether using push_front or push_back), only a single key is in the ECM.

-------------
Add classes that process Simulcrypt ECMG messages
1) Stream_set-up
2) CW_provision

-------------
Renames server and client binaries.

-------------
Make ecmg call ecm_generator to generate ecm. The return of the ecm to Simulcrypt caller will be implemented in the next CL.

For now, using the 'key' (control word) in CW_provision message also as the 'key_id'.

-------------
Move common folder

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=217358698

example/BUILD

@@ -0,0 +1,39 @@
+################################################################################
+# Copyright 2018 Google LLC.
+#
+# This software is licensed under the terms defined in the Widevine Master
+# License Agreement. For a copy of this agreement, please contact
+# widevine-licensing@google.com.
+################################################################################
+
+# Build file for the example code.
+
+package(
+    default_visibility = ["//visibility:public"],
+)
+
+
+filegroup(
+    name = "binary_release_files",
+    srcs = [
+        "simulcrypt_client.cc",
+        "test_simulcrypt_messages.h",
+        ":simulcrypt_client",
+    ],
+)
+
+cc_binary(
+    name = "simulcrypt_client",
+    srcs = ["simulcrypt_client.cc"],
+    deps = [
+        "//base",
+    ],
+)
+
+cc_library(
+    name = "test_simulcrypt_messages",
+    hdrs = ["test_simulcrypt_messages.h"],
+    deps = [
+        "//base",
+    ],
+)