Setup a new v8-poc package

This is a new package that depends on rusty-v8 for embedding a v8
engine.  This builds and works on non-musl platforms now because
rusty-v8 provides versions for that.  But we mocked out the loading of
a musl built library.

TODO: iterate on providing the musl built version for musl-linux builds.
TODO: create a release workflow for publishing the artifact that rusty-v8 can link against

third_party/v8/BUILD.bazel

@@ -0,0 +1,11 @@
+package(default_visibility = ["//visibility:public"])
+
+alias(
+    name = "rusty_v8_archive",
+    actual = ":rusty_v8_archive_placeholder",
+)
+
+filegroup(
+    name = "rusty_v8_archive_placeholder",
+    srcs = ["README.md"],
+)