core/api: move to core/proto

This is keeping in line with conventions that protobuf files generally
live in a 'proto/' directory. Even without that, a lot of the protos in
there aren't actually part of an API, so keeping them in `api/` is a bit
of a misnomer.

We also remove unused protos that were part of the old
integrity/lifecycle flow. Again, these will make a comeback.

Test Plan: this should fail. part of a larger stack. D590 is the first tip of the stack that should work.

X-Origin-Diff: phab/D588
GitOrigin-RevId: 4a7af494810348f6bcabd49e63902b4c47e6ec35
diff --git a/core/cmd/dbg/BUILD.bazel b/core/cmd/dbg/BUILD.bazel
index 7088ea1..3ca06d0 100644
--- a/core/cmd/dbg/BUILD.bazel
+++ b/core/cmd/dbg/BUILD.bazel
@@ -6,7 +6,7 @@
     importpath = "git.monogon.dev/source/nexantic.git/core/cmd/dbg",
     visibility = ["//visibility:private"],
     deps = [
-        "//core/api/api:go_default_library",
+        "//core/proto/api:go_default_library",
         "@com_github_spf13_pflag//:go_default_library",
         "@io_k8s_component_base//cli/flag:go_default_library",
         "@io_k8s_kubectl//pkg/cmd/plugin:go_default_library",