[Feature]: Improve scriptability/composability of CLI

[jaysoo]

What is the new or updated feature that you are suggesting?

It would be nice to have more insight into commands like watch and dev for scripting purposes.

Gatsby processes, for example, send structured messages via IPC so you can be notified when the server has been started, etc.

Why should this feature be included?

One scenario this would be useful is in test automation. For example, say I want to start an e2e test suite I need to do the following.

1. Start Remix (remix dev)
2. Wait for Remix server to start
3. Run my e2e suite (with Cypress, Playwright, etc.)
4. Wait for e2e to finish
5. Stop server

This scenario isn't easily scriptable currently since Step 2 requires manually checking if the port is ready (and the app server has started).