m/c/metroctl: embed installer and add argument for bundle

This embeds the installer in metroctl for easier distribution and adds
an option for passing a bundle path explicitly.

For the MVP this allows users to download metroctl and a bundle
separately and make an installer out of them.

Change-Id: I00f481c30a2e843d336248aad0dc4030d03c4576
Reviewed-on: https://review.monogon.dev/c/monogon/+/821
Tested-by: Jenkins CI
Reviewed-by: Mateusz Zalega <mateusz@monogon.tech>
diff --git a/metropolis/cli/metroctl/BUILD.bazel b/metropolis/cli/metroctl/BUILD.bazel
index 8175ca4..4b43c42 100644
--- a/metropolis/cli/metroctl/BUILD.bazel
+++ b/metropolis/cli/metroctl/BUILD.bazel
@@ -10,9 +10,11 @@
         "takeownership.go",
     ],
     data = [
-        "//metropolis/installer:kernel",
         "//metropolis/node:bundle",
     ],
+    embedsrcs = [
+        "//metropolis/installer:kernel",  #keep
+    ],
     importpath = "source.monogon.dev/metropolis/cli/metroctl",
     visibility = ["//visibility:private"],
     deps = [