fix: Fix loading Metro config from alternative config path

[huntie]

Summary

Resolves #2042. Config validation within loadMetroConfig was not passing options.config to Metro's resolveConfig function — where this is done later for loadConfig.

Test Plan

No --config arg (Unchanged)

✅ Implicitly loads ./metro.config.js

With --config specified

✅ Loads metro.config.js file from alternative file path

With --config specified, file does not exist

✅ Throws underlying error from Metro

(Note: This error message could be improved in Metro's source — to keep CLI lean I'm not wrapping this with anything now as the error is just about clear enough, cc @robhogan)

[szymonrybczak]

Thanks! 🙌

[szymonrybczak]

We need to release this change and backport to 0.72. cc. @thymikee

[thymikee]

@huntie mind creating a second PR targeting the 12.x branch please? 🙏🏼