Add dedicated update information reload

Currently we have the /refresh_updates endpoint which updates the main
component versions (Core, OS, Supervisor, Plug-ins) and the add-on
store at the same time. This combined update causes more update
information reloads than necessary.

To allow fine grained update refresh control introduce a new endpoint
/reload_updates which asks Supervisor to only update main component
versions (learned through the version json files).

The /store/reload endpoint already allows to update the add-on store
separately.

Author: agners

supervisor/api/__init__.py

@@ -346,6 +346,7 @@ def _register_root(self) -> None:
 
         self.webapp.add_routes([web.get("/info", api_root.info)])
         self.webapp.add_routes([web.post("/refresh_updates", api_root.refresh_updates)])
+        self.webapp.add_routes([web.post("/reload_updates", api_root.reload_updates)])
         self.webapp.add_routes(
             [web.get("/available_updates", api_root.available_updates)]
         )

supervisor/api/root.py

@@ -113,3 +113,8 @@ async def refresh_updates(self, request: web.Request) -> None:
         await asyncio.shield(
             asyncio.gather(self.sys_updater.reload(), self.sys_store.reload())
         )
+
+    @api_process
+    async def reload_updates(self, request: web.Request) -> None:
+        """Refresh updater update information."""
+        await self.sys_updater.reload()