🗺 Make entry.server and entry.client files optional

[ryanflorence]

Quick thoughts:

We'll need an RFC with more details on this and probably don't want root to be optional.

Discussed in #4601

^{Originally posted by mcansh November 14, 2022}
make entry.server and entry.client files optional would allow for quicker demos and getting started from nothing easier without having to use the remix cli to bootstrap an entire app. just install the dependencies and make a app/routes/index.tsx file and you're done. plus most folks don't touch these files anyways so making them optional and not need to be on disk* is an added bonus (they'll still be on disk, but you know what i mean)

by default it would look for the files and fallback to ones we have stored in @remix-run/dev, which would be copies from https://github.com/remix-run/remix/tree/main/templates/remix

[mcansh]

PR: #4600

[ryanflorence]

@mjackson to review the PR

[ryanflorence]

j/k get trolled, @jacob-ebey to review

[ryanflorence]

j/k get trolled they'll review it this week.

[github-actions]

🤖 Hello there,

We just published version v0.0.0-nightly-ecba23c-20230211 which involves this issue. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!