T861: add secure boot support. Build shim-signed package

Author: asklymenko

scripts/package-build/shim-signed/package.toml

@@ -2,3 +2,10 @@
 name = "shim-signed"
 commit_id = "rolling"
 scm_url = "https://github.com/vyos/shim-signed.git"
+
+[dependencies]
+packages = [
+    "shim-helpers-amd64-signed",
+    "shim-helpers-amd64-signed-template",
+    "shim-unsigned"
+]