build: Introduce Bazel build rules

So far this just compiles the core and common packages.

packages/common/BUILD

@@ -0,0 +1,13 @@
+package(default_visibility=["//visibility:public"])
+load("@io_bazel_rules_typescript//:defs.bzl", "ts_library")
+
+ts_library(
+    name = "common",
+    srcs = glob(["**/*.ts"], exclude=[
+      "test/**",
+      "testing/**",
+    ]),
+    module_name = "@angular/common",
+    deps = ["//packages/core"],
+    tsconfig = ":tsconfig-build.json",
+)