feat: an option for `bridgetown new` to create a fully dynamic application

[jaredcwhite]

Summary

Currently the default experience for a new Bridgetown site is a static site (with static pages like index.md), and server routes are completely optional. We should have an option to create a new project that only has dynamic routes and no static pages.

Motivation

Bridgetown can be used now to create fully-dynamic, database-driven, server-side applications, with all of our DX that's built on top of Roda. If that's possible, we should have an optional site template where this is the default.

Unresolved Questions

• Should we prompt users to pick from several topologies? (static, hybrid, dynamic) Or just offer a flag like --only-routes or whatever?
• Should we install a database plugin by default? (aka https://github.com/bridgetownrb/bridgetown_sequel)
• How much boilerplate/sample code should be installed out of the box?
• Should we add code generation functionality to our CLI so people can easily add new routes/controllers/views/etc. over time? (This would be a lot more opinionated than what we currently document.)