Add support for path dependencies from a package in one workspace to a
package in another workspace, which it self has workspace dependencies.
Say we have a main workspace with packages `a` and `b`, and a second
workspace with `c` and `d`. We have `a -> b`, `b -> c`, `c -> d`. This
would previously lead to a mangled path for `d`, which is now fixed.
Like distribution paths, we split workspace paths into an absolute
install path and a relative (or absolute, if the user provided an
absolute path) lock path.
Part of https://github.com/astral-sh/uv/issues/3943
konsti
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