fix(forge): populate the git submodule url from git config

[wellnana]

The Dependency::FromStr implementation sets url to None when the input is treated as an alias-only dependency, eg forge-std, so we can try to get the url from the git config.

[onbjerg]

The test is failing

[wellnana]

The test is failing

Ah, I shouldn't change cmd.rs revert now, not sure why its flaky test here, but should be good this time