Setup pw_web_ui with Bazel and Jasmine

Initialize the pw_web_ui package and add Bazel as a build system. Add a single example test in `src/transport/web_serial_transport_test.ts` to verify Bazel can build and run Jasmine tests.

HAS_TO_BE_LARGE=Initializing a new package. Most of this is due to yarn.lock.

Change-Id: Ie3adbdba5a91de9a5f16205be8077bafb3a1fee3
diff --git a/pw_web_ui/BUILD b/pw_web_ui/BUILD
new file mode 100644
index 0000000..2c8334f
--- /dev/null
+++ b/pw_web_ui/BUILD
@@ -0,0 +1,13 @@
+# Copyright 2020 The Pigweed Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License. You may obtain a copy of
+# the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations under
+# the License.