Feature Request: Add a "Packages Path" field to wally.toml

[jisham318]

Currently wally saves imported packages to "./Packages/", In a future release, I would like to see a feature where we're able to change the default path to a different folder.
Heck, this actually might be something I'd create a PR for if I decide to take the time to learn Rust and learn the innards of this utility.