[router]: Fix fast refresh on layout files

[marklawlor]

Why

Fix Fast Refresh on _layout files that export unstable_settings and/or ErrorBoundary.

How

Metro's FastRefresh implementation has a set of rule that Expo Router does not follow causing full app reloads.

Next.js is a similar framework to Expo Router which has resolved the issue in a similar fashion. In the Next.js implementation they

• Use Babel to rename the exports to prevent false positive (e.g getStaticProps/getStaticPaths are bundled into a __N_SSG export`
• Replace ReactRefresh with their own extended version

While the Next.js solution is more robust, I believe this solution is simple enough for our current needs.

Possible additional changes:

• tag ErrorBoundary and the ctx export with a Symbol and use that for isLikelyComponentType detection
• Ensure unstable_settings only exists on a module with a default export
• Mutate unstable_settings during getRoutes with a Symbol and use that for isLikelyComponentType detection

Test Plan

npx create-expo-app app

• Set some local state (e.g going to a tab)
• Modify the _layout file

Checklist

• Documentation is up to date to reflect these changes (eg: https://docs.expo.dev and README.md).
• Conforms with the Documentation Writing Style Guide
• This diff will work correctly for npx expo prebuild & EAS Build (eg: updated a module plugin).

[marklawlor]

• Add static params functions
• Add e2e test (template: https://github.com/expo/expo/blob/@evanbacon/metro/treeshake-2/packages/@expo/cli/e2e/playwright/dev/fast-refresh.test.ts)