Drop recursive readlink when we drop Node 10

Node 10 on Windows throws a EPERM when we `fs.stat` on a symlink to a directory. We work around this by recursively readlink on symlinks found by source, but we can remove this workaround when we drop Node 10 support.

_Originally posted by @phated in https://github.com/gulpjs/vinyl-fs/pull/333#discussion_r1225647122_

Start by locating the recursive readlink workaround used for symlinks found by source, then inspect any related tests. Confirm that Node 10 support has been dropped before removing the workaround, and run the relevant test suite to verify symlink handling still passes.

Written by the indexing model from the issue text.