Allow configuring metro root

[janicduplessis]

Describe the Feature

AFAIK it is currently impossible to configure the metro root from the cli config file. This is the only thing missing to make it work properly in a monorepo setup where the metro root is the repo root and projects use entry points like apps/app/index. This setup allows running multiple apps on a single metro instance.

Possible Implementations

This could use a value from userConfig if provided

cli/packages/cli/src/tools/config/index.js

Line 70 in 9e3134b

root: projectRoot,

Another alternative that might be better is make it so the metro config for projectRoot (metro.config.js) actually works. Seems like it is currently ignored.

Related Issues

N/A