Call scarb metadata recursively for dependencies that are not inside workspace

[piotmag769]

This would let us know the image of all dependencies and their dev-dependencies in advance instead of getting to know them on goto to a dependency.

We could limit it to depth = 1 to make sure the performance is not hurt in any significant way. We should probably also call schedule additional metadata calls only when in the idle state.

Potentially the biggest drawback would be calculating proc macros on tests from immediate dependencies even when they were never opened.