m/p/localregistry: init

Adds the localregistry package, which serves Bazel-built container
images via the Docker/OCI V2 registry API.

This will be used to serve test images instead of preseeding them.

Change-Id: I0c2ceb9a83f807c9c87ab03bc1141ca67cc64268
Reviewed-on: https://review.monogon.dev/c/monogon/+/1926
Tested-by: Jenkins CI
Reviewed-by: Leopold Schabel <leo@monogon.tech>
diff --git a/metropolis/pkg/localregistry/spec/gomod-generated-placeholder.go b/metropolis/pkg/localregistry/spec/gomod-generated-placeholder.go
new file mode 100644
index 0000000..f09cd57
--- /dev/null
+++ b/metropolis/pkg/localregistry/spec/gomod-generated-placeholder.go
@@ -0,0 +1 @@
+package spec