Add `@zfig/fastify` and `@zfig/express` as syntactic sugar for `@zfig/bootstrap`

[rstagi]

They implement it as a fastify or expreess servers already. DevX would be something like:

import { bootstrap } from '@zfig/fastify';

export default bootstrap(
  configSchema,
  { ...options... },
  async (fastify) => { // instead of `config` we already have `fastify` with `fastify.config` if needed
    // ... configure fastify ...
    // ... no need to return fastify ...
  },
);