Add minimal functionality test for k8s control plane

Basic functionality test that sends the bootstrap RPC call,
waits for the k8s control plane to come up and runs a simple
kubectl command (that is expected to fail).

Adds reflection to the server to make grpc_cli easier to use.

Test Plan:
Ran `:launch` (because we modified its config) and `:test_boot`,
saw a nicely booted k8s cluster:

{P90}

X-Origin-Diff: phab/D275
GitOrigin-RevId: fe01e3f3ed09877aa76c15946664c9d9bdc4751b
diff --git a/core/internal/api/BUILD.bazel b/core/internal/api/BUILD.bazel
index b7aa48d..3daa397 100644
--- a/core/internal/api/BUILD.bazel
+++ b/core/internal/api/BUILD.bazel
@@ -16,6 +16,7 @@
         "//core/internal/common/service:go_default_library",
         "//core/internal/consensus:go_default_library",
         "@org_golang_google_grpc//:go_default_library",
+        "@org_golang_google_grpc//reflection:go_default_library",
         "@org_uber_go_zap//:go_default_library",
     ],
 )