Normalize `--path` to install bin outside current workspace

Normalize `--path` to install bin outside current workspace

For `Workspace::find_root`, `cargo_util::path::PathAncestors` won't do
path normalization while walking back the ancestors. The responsibility
lies in the caller. Thus, `cargo install` should normalize its `--path`
argument before passing in `SourceId::for_path` and `Workspace::new`.

`Config::reload_rooted_at` is not affected because cargo always starts
searching and merging configs from where it is invoked.