feat: add client plugin to honox/vite

[yusukebe]

Then you don't have to write:

export default defineConfig(({ mode }) => {
  if (mode === 'client') {
    return {
      build: {
        rollupOptions: {
          input: ['/app/style.css']
        }
      },
      plugins: [clientBuild()]
    }
  } else {
    return {
      plugins: [
        honox({
          devServer: {
            adapter
          }
        }),
        ssrBuild()
      ]
    }
  }
})

Instead of it, you can write it shortly:

export default defineConfig({
  plugins: [
    honox({
      devServer: {
        adapter
      },
      client: {
        input: ['/app/style.css']
      }
    }),
    pages()
  ]
})