Add HMR support for schema reloads

[tobiasdiez]

Requires vitejs/vite#10324 and vitejs/vite#10333 (Vite 3.2, which is in nuxt rc 13). Then the following should work:

    let viteServer: ViteDevServer | undefined;
    if (nuxt.options.dev) {
      nuxt.hook('vite:serverCreated', (devServer: ViteDevServer, ctx) => {
        if (ctx.isServer) {
          viteServer = devServer;
        }
      });
    }
    // If schema file changes:
    viteServer.reloadModule("#graphql/schema") 

Same for updating the template using updateTemplate, which will be introduced in nuxt rc13.