perf: resolution should not be blocked by fetching packages to the store

[zkochan]

The resolution stage should not be blocked by the fetch stage. Once we resolve a dependency, we should immediately proceed to resolving its own dependencies. Fetching of packages to the store should happen in parallel.

Currently, resolution is blocked by fetching packages to the store as seen in this function:

https://github.com/pnpm/pacquet/blob/f66d64c886474ec7b587ce330d6db54ad9966879/crates/cli/src/package.rs#L17-L29