Previously, if there were path-mapped entry-points, where one contaied the
string of another - for example `worker-client` and `worker` - then the
base paths were incorrectly computed resulting in the wrong package path
for the longer entry-point. This was because, when searching for a matching
base path, the strings were tested using `startsWith()`, whereas we should
only match if the path was contained in a directory from a file-system
point of view.
Now we not only check whether the target path "starts with" the base path
but then also whether the target path is actually contained in the base path
using `fs.relative()`.
Fixes#40352Fixes#40357
PR Close#40376
afd11662a3