Previously, ngcc had to walk the entire `node_modules` tree looking for
entry-points, even if it only needed to process a single target entry-point
and its dependencies.
This added up to a few seconds to each execution of ngcc, which is noticeable
when being run via the CLI integration.
Now, if an entry-point target is provided, only that target and its entry-points
are considered rather than the whole folder tree.
PR Close#30525