feat(cli): Add metro favicon middleware (#23072)

# Why

- Expo Webpack had support and this was a nice feature.

<!--
Please describe the motivation for this PR, and link to relevant GitHub
is

feat(cli): Add metro favicon middleware (#23072)

# Why

- Expo Webpack had support and this was a nice feature.

<!--
Please describe the motivation for this PR, and link to relevant GitHub
issues, forums posts, or feature requests.
-->

# How

- Add middleware in development for `/favicon.ico` which generates a
favicon based on the config in `app.json` `web.favicon`

<!--
How did you build this feature or fix this bug and why?
-->

# Test Plan

- Added tests. They're not fully exhaustive and don't cover the `single`
export case.


<!--
Please describe how you tested this change and how a reviewer could
reproduce your test, especially if this PR does not include automated
tests! If possible, please also provide terminal output and/or
screenshots demonstrating your test/reproduction.
-->

# Checklist

<!--
Please check the appropriate items below if they apply to your diff.
This is required for changes to Expo modules.
-->

- [ ] Documentation is up to date to reflect these changes (eg:
https://docs.expo.dev and README.md).
- [ ] Conforms with the [Documentation Writing Style
Guide](https://github.com/expo/expo/blob/main/guides/Expo%20Documentation%20Writing%20Style%20Guide.md)
- [ ] This diff will work correctly for `npx expo prebuild` & EAS Build
(eg: updated a module plugin).

---------

Co-authored-by: Expo Bot <[email protected]>

show more ...