Open Source KWS Streaming Tests (#3478)

Open sources tests of [kws_steaming](https://github.com/google-research/google-research/tree/master/kws_streaming) models by adding a Bazel `http_archive` and `BUILD.overlay`.

The longest of these tests complete in ~60s, so they shouldn't add a significant amount of time to the CI.

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index a6db513..25c8a0e 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -299,5 +299,15 @@
     path = "third_party/cpuinfo",
 )
 
+GOOGLE_RESEARCH_COMMIT = "1dbf7f4af77ac032ddcf68a7978cc056897015a7"
+
+http_archive(
+    name = "kws_streaming",
+    build_file = "@//:build_tools/third_party/kws_streaming/BUILD.overlay",
+    sha256 = "cdb0b71914999a9cb11b5a80eb16769687c9714d9ac706e6c1cf081c3afbd976",
+    strip_prefix = "google-research-{}/kws_streaming".format(GOOGLE_RESEARCH_COMMIT),
+    url = "https://github.com/google-research/google-research/archive/{}.tar.gz".format(GOOGLE_RESEARCH_COMMIT),
+)
+
 # Bootstrap TensorFlow deps last so that ours can take precedence.
 tf_repositories()