feat(new): add option to choose between Express and Fastify

[Zerotask]

I'm submitting a...

[ ] Regression 
[ ] Bug report
[x] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

At the moment Express will be used as it is the default.

Expected behavior

Got asked if I want to use Express (default, selected) or Fastify.

Minimal reproduction of the problem with instructions

What is the motivation / use case for changing the behavior?

Since Express isn't maintained anymore / receives way less updates than Fasitfy, I always use Fastify for such cases. Therefore, for Nest applications I always switch to Fasitfy.
It is also mentioned as a faster alternative (If you believe benchmarks). Those are 2 plus points for Fastify.

Environment

[System Information]
OS Version     : Windows 10
NodeJS Version : v16.9.0
NPM Version    : 7.21.1

[Nest CLI]
Nest CLI Version : 8.1.1

[kamilmysliwiec]

A project generated by the nest new command is a starting point, boilerplate code for HTTP-based apps, microservices (all built-in transports + custom ones), real-time WS-based apps, etc. We discussed this in the past and adding an option to switch to Fastify without allowing people to choose all the other alternative variants (gRPC/Nats/Kafka/just Socket.io or WS) might be confusing. So far we have decided to just keep the nest new flow as simple as we can.