fix(javascript/rest-fastify): improvements

[Aperrix]

• Add fastify-blipp to display availables routes in dev env
• Fix response typo (from res.send to return because req is async)
• Fix server start function

[2color]

Thanks for the PR @Aperrix.

For simplicity, I'd remove the fastify-blipp plugin.

I left a couple of small comments.

Finally, be sure to run prettier for consistent code style.

[janpio]

Can you take another look at this @Aperrix? Thanks.

[ruheni]

Closed this in favor of #4233