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/build/Dockerfile b/build/Dockerfile
index f994bb5..3fdfc68 100644
--- a/build/Dockerfile
+++ b/build/Dockerfile
@@ -25,7 +25,9 @@
 	rsync \
 	qemu-system-x86-core \
 	postgresql \
-	expect
+	expect \
+	grpc-cli \
+	nc
 
 # Workaround for a binutils bugs in F30, which generates invalid ELF binaries
 # when linking statically with musl.