Adds a new Builder for the Remix framework. This Builder has support for a few different configurations of Remix including the "just the basics" Remix server as well as the "vercel" server build target configuration. If the project does not have the `@remix-run/vercel` runtime adapter as a dependency in package.json then this Builder will implicitly add it when generating the SSR serverless function.
In a follow-up PR, we can make this Builder be used in the frameworks configuration so that it is executed when `remix` framework is selected for the project, and we can update the remix example template in this repo to no longer require the `ENABLE_FILE_SYSTEM_API` env var.
