treewide: move build helper to more fitting places

Change-Id: I3d0cfe9283222d403ae369ec9db09201ad511e15
Reviewed-on: https://review.monogon.dev/c/monogon/+/3327
Reviewed-by: Serge Bazanski <serge@monogon.tech>
Tested-by: Jenkins CI
diff --git a/osbase/build/mkimage/osimage/BUILD.bazel b/osbase/build/mkimage/osimage/BUILD.bazel
new file mode 100644
index 0000000..cfcf096
--- /dev/null
+++ b/osbase/build/mkimage/osimage/BUILD.bazel
@@ -0,0 +1,15 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "osimage",
+    srcs = ["osimage.go"],
+    importpath = "source.monogon.dev/osbase/build/mkimage/osimage",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//osbase/blockdev",
+        "//osbase/efivarfs",
+        "//osbase/fat32",
+        "//osbase/gpt",
+        "@com_github_google_uuid//:uuid",
+    ],
+)