Fix session replica behaviour (merge with session)

The harder-to-refactor parts are the places where exists/username/token
are called within a React component. However, `resetAndRedirect` and
`store` are already called from async contexts, so adding an `await`
is simple.

This thus merges the logic, keeping localStorage for the components to
call, but making sure reset/store behaviour works correctly for the
replica.

web/src/components/hooks.js

@@ -114,7 +114,7 @@ export const useAutoSubscribe = (subscriptions, selected) => {
           } catch (e) {
             console.log(`[Hooks] Auto-subscribing failed`, e);
             if (e instanceof UnauthorizedError) {
-              session.resetAndRedirect(routes.login);
+              await session.resetAndRedirect(routes.login);
             }
           }
         }