[Feature] Add warning for script sizes over 1MB

[ItsWendell]

• Cloudflare Workers are limited to 1MB in size: https://developers.cloudflare.com/workers/platform/limits#script-size
• Miniflare still works but doesn't warn users when their scripts are bigger than 1Mb in size.
• Might be useful to give users a warning so we know that that's the case.

[mrbbot]

This would be really useful, and definitely help with the problem of something working on Miniflare but in production. 👍

[mrbbot]

Just released version 1.4.0 with this. Please let me know if you have any other issues or feedback. 😄

[SupremeTechnopriest]

Paid worker plans allow workers up to 5mb. Can we add a miniflare config option that allows us to specify if the worker is on a paid plan?