core: Add composefs digest for local commits too

This pairs with dbe7821
where we generate composefs metadata for base images.

It's going to be useful to do it for client side builds too, so
that we can treat them symmetrically.  It doesn't have
a very high cost, just a metadata traversal.

src/libpriv/rpmostree-core.cxx

@@ -4713,6 +4713,19 @@ rpmostree_context_commit (RpmOstreeContext *self, const char *parent,
         if (!ostree_commit_metadata_for_bootable (root, metadata_dict, cancellable, error))
           return FALSE;
       }
+#if OSTREE_CHECK_VERSION(2023, 4)
+    {
+      g_autoptr (GError) local_error = NULL;
+      if (!ostree_repo_commit_add_composefs_metadata (
+              self->ostreerepo, 0, metadata_dict, (OstreeRepoFile *)root, cancellable, &local_error)
+          && !g_error_matches (local_error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED))
+        {
+          g_propagate_prefixed_error (error, util::move_nullify (local_error),
+                                      "Adding composefs metadata");
+          return FALSE;
+        }
+    }
+#endif
     g_autoptr (GVariant) metadata = g_variant_dict_end (metadata_dict);
 
     {

tests/kolainst/destructive/layering-local

@@ -74,8 +74,11 @@ if ostree ls "${booted_commit}" /run/ostree-booted 2>/dev/null; then
 fi
 
 ostree show --print-metadata-key=ostree.bootable ${booted_commit} >out.txt
-assert_file_has_content_literal out.txt 'true'
+assert_file_has_content_literal out.txt 'byte'
 echo "ok bootable metadata"
+ostree show --print-metadata-key=ostree.composefs.digest.v0 ${booted_commit} >out.txt
+assert_file_has_content_literal out.txt 'true'
+echo "ok composefs metadata on client generated commit"
 
 # check we could uninstall the package using either its NEVRA or name
 rpm-ostree uninstall foo-1.2-3.x86_64