fix(fs): correct ReadLink error message and add missing read_link wra…

[gap-editor]

My PR fixes a small inconsistency in the fs utilities module:

Fixed: the FsPathError::ReadLink message was identical to Read ("failed to read from …"), which made it hard to distinguish link read failures in logs.
Now it clearly says “failed to read link …”.
Added: the missing read_link() wrapper for std::fs::read_link, providing consistent API coverage and error context like other helpers (read(), write(), read_dir()).

[mattsse]

this seems appropriate even tho we don't use it, just in case we want to extract all of this at some point