[bazel] Initialize bazel configuration.

1. Create a WORKSPACE file to initialize the embedded compiler configuration
and provide googletest and abseil dependencies.
2. Pin the bazel version to 4.2.0 (current version).
3. Create an empty BUILD file in the root of the project.

Signed-off-by: Chris Frantz <cfrantz@google.com>
diff --git a/BUILD b/BUILD
new file mode 100644
index 0000000..ffd0fb0
--- /dev/null
+++ b/BUILD
@@ -0,0 +1 @@
+package(default_visibility = ["//visibility:public"])