registry admin script (#2426)

* registryadmin scripts

Add `start-sdk publish` command which can potentially replace
the Haskell implementation of `registry-publish upload`

* restructure modules

---------

Co-authored-by: Sam Sartor <me@samsartor.com>

backend/src/s9pk/manifest.rs

@@ -112,7 +112,7 @@ pub struct HardwareRequirements {
     #[serde(default)]
     device: BTreeMap<String, Regex>,
     ram: Option<u64>,
-    arch: Option<Vec<String>>,
+    pub arch: Option<Vec<String>>,
 }
 
 #[derive(Clone, Debug, Default, Deserialize, Serialize)]